Anti-CSF1R Antibody and Anti PD-1 Antibody Combination Therapy for Cancer

ABSTRACT

Methods of treating cancer with antibodies that bind colony stimulating factor 1 receptor (CSF1R) in combination with PD-1/PD-L1 inhibitors are provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional of U.S. application Ser. No.15/680,664, filed Aug. 18, 2017, which is a continuation of U.S.application Ser. No. 14/925,534, filed Oct. 28, 2015, now U.S. Pat. No.9,765,147, which claims the benefit of priority of US ProvisionalApplication Nos. 62/072,035, filed Oct. 29, 2014, 62/157,368, filed May5, 2015, and 62/192,025, filed Jul. 13, 2015, all of which areincorporated by reference herein in their entirety for any purpose.

SEQUENCE LISTING

The present application is filed with a Sequence Listing in electronicformat. The Sequence Listing is provided as a file entitled“01134-0036-00US_SeqList_ST25.txt” created on Oct. 28, 2015, which is167,217 bytes in size. The information in the electronic format of thesequence listing is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Methods of treating cancer with antibodies that bind colony stimulatingfactor 1 receptor (CSF1R) in combination with PD-1/PD-L1 inhibitors.

BACKGROUND

Colony stimulating factor 1 receptor (referred to herein as CSF1R; alsoreferred to in the art as FMS, FIM2, C-FMS, M-CSF receptor, and CD115)is a single-pass transmembrane receptor with an N-terminal extracellulardomain (ECD) and a C-terminal intracellular domain with tyrosine kinaseactivity. Ligand binding of CSF1 or the interleukin 34 ligand (referredto herein as IL-34; Lin et al., Science 320: 807-11 (2008)) to CSF1Rleads to receptor dimerization, upregulation of CSF1R protein tyrosinekinase activity, phosphorylation of CSF1R tyrosine residues, anddownstream signaling events. CSF1R activation by CSF1 or IL-34 leads tothe trafficking, survival, proliferation, and differentiation ofmonocytes and macrophages, as well as other monocytic cell lineages suchas osteoclasts, dendritic cells, and microglia.

Many tumor cells or tumor stromal cells have been found to produce CSF1,which activates monocyte/macrophage cells through CSF1R. The level ofCSF1 in tumors has been shown to correlate with the level oftumor-associated macrophages (TAMs) in the tumor. Higher levels of TAMshave been found to correlate with poorer patient prognoses in themajority of cancers. In addition, CSF1 has been found to promote tumorgrowth and progression to metastasis in, for example, human breastcancer xenografts in mice. See, e.g., Paulus et al., Cancer Res. 66:4349-56 (2006). Further, CSF1R plays a role in osteolytic bonedestruction in bone metastasis. See, e.g., Ohno et al., Mol. CancerTher. 5: 2634-43 (2006). TAMs promote tumor growth, in part, bysuppressing anti-tumor T cell effector function through the release ofimmunosuppressive cytokines and the expression of T cell inhibitorysurface proteins.

Genetic alterations in cancer provide a diverse set of antigens that canmediate anti-tumor immunity. Antigen recognition through T-cellreceptors (TCRs) initiate T-cell-responses, which are regulated by abalance between activating and inhibitory signals. The inhibitorysignals, or “immune checkpoints,” play an important role in normaltissues by preventing autoimmunity. Up-regulation of immune checkpointproteins allows cancers to evade anti-tumor immunity. Two immunecheckpoint proteins have been the focus of clinical cancerimmunotherapeutics, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4)and programmed cell death protein 1 (PD-1). The combination of ananti-CTLA-4 antibody and an anti-PD-1 antibody has been approved for thetreatment of metastatic melanoma and several additional clinical trialsare also ongoing to study the use of this combination for the treatmentof other cancers. Anti-PD-1 antibodies and anti-CTLA-4 antibodies foruse as monotherapies are also currently being studied in clinical trialsas a treatment for many different types of cancer. Anti-PD-L1 antibodieswhich bind PD-L1, one of the ligands for PD-1, are also currently inclinical development.

Many tumors often express multiple checkpoint molecules simultaneously,Therefore, combinations of checkpoint modulators are undergoing clinicaltesting with aim of improved efficacy. Initial clinical results of thecombination of an anti-CTLA-4 antibody (anti-CTLA-4 Ab) and an anti-PD-1antibody (anti-PD-1 Ab) have demonstrated improved overall responserates, increased complete response rates, as well as overall survivalrates in metastatic melanoma, compared to anti-CTLA-4 Ab alone orhistorical controls.

As described herein, significant antitumor activity of an anti-PD-1antibody in combination with an anti-CSF1R antibody has beendemonstrated in clinical trials.

SUMMARY

In some embodiments, methods of treating cancer in a subject areprovided, comprising administering to the subject an anti-CSF1R antibodyand a PD-1/PD-L1 inhibitor. In some embodiments, the PD-1/PD-L1inhibitor is an antibody. In some embodiments, the PD-1/PD-L1 inhibitoris an anti-PD-1 antibody. In some embodiments, the anti-PD-1 antibodycomprises the heavy chain and light chain CDRs of an antibody selectedfrom nivolumab and pembrolizumab. In some embodiments, the anti-PD-1antibody comprises the heavy chain and light chain variable regions ofan antibody selected from nivolumab and pembrolizumab. In someembodiments, the anti-PD-1 antibody is selected from nivolumab andpembrolizumab. In some embodiments, the PD-1/PD-L1 inhibitor is ananti-PD-L1 antibody. In some embodiments, the anti-PD-L1 antibodycomprises the heavy chain and light chain CDRs of an antibody selectedfrom BMS-936559, MPDL3280A, MEDI4736, and MSB0010718C. In someembodiments, the anti-PD-L1 antibody comprises the heavy chain and lightchain variable regions of an antibody selected from BMS-936559,MPDL3280A, MEDI4736, and MSB0010718C. In some embodiments, theanti-PD-L1 antibody is selected from BMS-936559, MPDL3280A, MEDI4736,and MSB0010718C. In some embodiments, the PD-1/PD-L1 inhibitor is afusion protein. In some embodiments, the fusion protein is AMP-224.

In some embodiments, the anti-CSF1R antibody and the PD-1/PD-L1inhibitor are administered concurrently or sequentially. In someembodiments, the anti-CSF1R antibody and the PD-1/PD-L1 inhibitor areadministered concurrently. In some embodiments, one or more doses of thePD-1/PD-L1 inhibitor are administered prior to administering ananti-CSF1R antibody. In some embodiments, the subject received acomplete course of PD-1/PD-L1 inhibitor therapy prior to administrationof the anti-CSF1R antibody. In some embodiments, the anti-CSF1R antibodyis administered during a second course of PD-1/PD-L1 inhibitor therapy.In some embodiments, the subject received at least one, at least two, atleast three, or at least four doses of the PD-1/PD-L1 inhibitor prior toadministration of the anti-CSF1R antibody. In some embodiments, at leastone dose of the PD-1/PD-L1 inhibitor is administered concurrently withthe anti-CSF1R inhibitor. In some embodiments, one or more doses of theanti-CSF1R antibody are administered prior to administering a PD-1/PD-L1inhibitor. In some embodiments, the subject received at least two, atleast three, at least three, or at least four doses of the anti-CSF1Rantibody prior to administration of the PD-1/PD-L1 inhibitor. In someembodiments, at least one dose of the anti-CSF1R antibody isadministered concurrently with the PD-1/PD-L1 inhibitor. In someembodiments, the two drugs are administered on the same day. In someembodiments, the drugs are mixed together prior to administration andthus administered as a mixture. For example, in some embodiments, thedrugs may be packaged and stored in the same vial (i.e., fixed doseformulation), or alternatively, vials containing each separate drug maybe mixed together just prior to administration. In various embodiments,the drugs may be administered in vivo by various routes, including, butnot limited to, oral, intra-arterial, parenteral, intranasal,intravenous, intramuscular, intracardiac, intraventricular,intratracheal, buccal, rectal, intraperitoneal, intradermal, topical,transdermal, and intrathecal, or otherwise by implantation orinhalation.

In some embodiments, the anti-CSF1R antibody is administered at a doseof about 0.1, about 0.3, about 0.5, about 1, about 2, about 3, about 4,about 5 or about 10 mg/kg. In some embodiments, the PD-1/PD-L1 inhibitoris administered at a dose of 0.1-10 mg/kg, such as, for example about0.1, about 0.3, about 0.5, about 1, about 2, about 3, about 4, about 5or about 10 mg/kg mg/kg. In some embodiments, the anti-CSF1R antibodyand the PD-1/PD-L1 inhibitor are administered, for example at one of theabove doses, about once per 1, 2, 3, 4, or 5 weeks, such as about onceevery 2 weeks.

In certain embodiments, the first dose is a therapeutic dose and thesecond dose is a therapeutic dose. In other embodiments, the first doseis a subtherapeutic dose and the second dose is a therapeutic dose. Insome embodiments, the first dose is administered at a dose ranging fromat least about 80 mg to at least about 800 mg or at least about 0.1mg/kg to at least about 10.0 mg/kg body weight. In some embodiments, thesecond dose is administered at a dose ranging from at least about 80 mgto at least about 800 mg or at least about 0.1 mg/kg to at least about10.0 mg/kg body weight. In one particular embodiment, the first dose isadministered at a dose of at least about 3 mg/kg body weight or 240 mgonce about every 2 weeks.

In some embodiments, the subject is administered at least two doses, atleast three doses, at least four doses, at least five doses, at leastsix doses, at least seven doses, at least eight doses, at least ninedoses, at least ten doses, at least 12 doses, at least 20 doses.

In some embodiments, the first dose is a flat dose or a weight baseddose. In other embodiments, the second dose is a flat dose or a weightbased dose.

In some embodiments, the cancer is selected from non-small cell lungcancer, melanoma, squamous cell carcinoma of the head and neck, ovariancancer, pancreatic cancer, renal cell carcinoma, hepatocellularcarcinoma, bladder cancer, and endometrial cancer. In some embodiments,the cancer is a central nervous system neoplasm. In some embodiments,the central nervous system neoplasm is a malignant glioma orglioblastoma. In some embodiments, the cancer is recurrent orprogressive after a therapy selected from surgery, chemotherapy,radiation therapy, or a combination thereof. In some embodiments, thepatient has stage III or stage IV cancer, as defined in the definitionssection below with respect to particular cancers. In some embodiments,the patient's cancer is metastatic. In some embodiments, the subject isa PD-1/PD-L1 inhibitor inadequate responder or is refractory to priortreatment with a PD-1/PD-L1 inhibitor. In some embodiments, the subjecthas previously received PD-1/PD-L1 inhibitor therapy, and in otherembodiments the subject has not previously received PD-1/PD-L1 inhibitortherapy. In some embodiments, the patient has previously received one ormore of chemotherapy, radiation therapy, or surgery; in some suchembodiments the patient has documented tumor progression in spite ofsuch prior treatment. In some embodiments, administration of theanti-CSF1R antibody and the PD-1/PD-L1 inhibitor results in asynergistic effect on tumor growth, weight, and/or volume compared in amouse xenograft model for the cancer compared to administration of theanti-CSF1R antibody or PD-1/PD-L1 inhibitor alone.

In some embodiments of the methods a patient with non-small cell lungcancer (NSCLC) is treated with the anti-CSF1R antibody (for instance, ananti-CSF1R antibody as described herein, such as an antibody comprisingthe heavy and light chain CDRs of HuAB1) and the PD-1/PD-L1 inhibitor(for instance, an anti-PD-1 antibody comprising the heavy chain andlight chain CDRs of nivolumab or pembrolizumab or a PD-1/PD-L1 inhibitorfusion protein or peptide such as AMP-224 or AUR-012). In some suchembodiments, the patient has Stage IIIB or IV disease and/or hasdemonstrated disease progression or recurrence during and/or after aplatinum doublet-based or other chemotherapy regimen for advanced ormetastatic disease. In some embodiments, the patient has not had priorexposure to a PD-1/PD-L1 inhibitor, and in other embodiments, thepatient is refractory to PD-1/PD-L1 inhibitor treatment. In someembodiments, the anti-CSF1R antibody is administered at a dose of about0.1, about 0.3, about 0.5, about 1, about 2, about 3, about 4, about 5or about 10 mg/kg. In some embodiments, the PD-1/PD-L1 inhibitor isadministered at a dose of 0.1-10 mg/kg, such as, for example about 0.1,about 0.3, about 0.5, about 1, about 2, about 3, about 4, about 5 orabout 10 mg/kg mg/kg. In some embodiments, the anti-CSF1R antibody andthe PD-1/PD-L1 inhibitor are administered, for example at one of theabove doses, once per 1, 2, 3, 4, or 5 weeks, such as about once every 2weeks. In some embodiments, administration of the anti-CSF1R antibodyand the PD-1/PD-L1 inhibitor results in a synergistic effect on tumorgrowth, weight, and/or volume compared in a mouse xenograft model forNSCLC compared to administration of the anti-CSF1R antibody orPD-1/PD-L1 inhibitor alone.

In some embodiments of the methods, melanoma is treated with theanti-CSF1R antibody (for instance, an anti-CSF1R antibody as describedherein, such as an antibody comprising the heavy and light chain CDRs ofHuAB1) and the PD-1/PD-L1 inhibitor (for instance, an anti-PD-1 antibodycomprising the heavy chain and light chain CDRs of nivolumab orpembrolizumab or a PD-1/PD-L1 inhibitor fusion protein or peptide suchas AMP-224 or AUR-012). In some such embodiments, the patient has StageIII or IV melanoma. In some embodiments, the patient has demonstrateddisease progression during or after treatment with at least one BRAFinhibitor, or is BRAF wild-type. In some embodiments, the patient hasnot had prior exposure to a PD-1/PD-L1 inhibitor, and in otherembodiments, the patient is refractory to PD-1/PD-L1 inhibitortreatment. In some embodiments, the anti-CSF1R antibody is administeredat a dose of about 0.1, about 0.3, about 0.5, about 1, about 2, about 3,about 4, about 5 or about 10 mg/kg. In some embodiments, the PD-1/PD-L1inhibitor is administered at a dose of 0.1-10 mg/kg, such as, forexample about 0.1, about 0.3, about 0.5, about 1, about 2, about 3,about 4, about 5 or about 10 mg/kg mg/kg. In some embodiments, theanti-CSF1R antibody and the PD-1/PD-L1 inhibitor are administered, forexample at one of the above doses, once per 1, 2, 3, 4, or 5 weeks, suchas about once every 2 weeks. In some embodiments, administration of theanti-CSF1R antibody and the PD-1/PD-L1 inhibitor results in asynergistic effect on tumor growth, weight, and/or volume compared in amouse xenograft model for melanoma compared to administration of theanti-CSF1R antibody or PD-1/PD-L1 inhibitor alone.

In some embodiments of the methods, squamous cell carcinoma of the headand neck (SSCHN) is treated with the anti-CSF1R antibody (for instance,an anti-CSF1R antibody as described herein, such as an antibodycomprising the heavy and light chain CDRs of HuAB1) and the PD-1/PD-L1inhibitor (for instance, an anti-PD-1 antibody comprising the heavychain and light chain CDRs of nivolumab or pembrolizumab or a PD-1/PD-L1inhibitor fusion protein or peptide such as AMP-224 or AUR-012). In someembodiments, the patient has Stage III or IV SSCHN or has recurrent ormetastatic SSCHN. In some embodiments, the patient has previouslyreceived chemotherapy, such as platinum therapy, but has demonstratedtumor progression or recurrence. In some embodiments, the patient haspreviously received radiation therapy, optionally along with platinumtherapy, but has demonstrated tumor progression or recurrence. In someembodiments, the patient has not had prior exposure to a PD-1/PD-L1inhibitor, and in other embodiments, the patient is refractory toPD-1/PD-L1 inhibitor treatment. In some embodiments, the anti-CSF1Rantibody is administered at a dose of about 0.1, about 0.3, about 0.5,about 1, about 2, about 3, about 4, about 5 or about 10 mg/kg. In someembodiments, the PD-1/PD-L1 inhibitor is administered at a dose of0.1-10 mg/kg, such as, for example about 0.1, about 0.3, about 0.5,about 1, about 2, about 3, about 4, about 5 or about 10 mg/kg mg/kg. Insome embodiments, the anti-CSF1R antibody and the PD-1/PD-L1 inhibitorare administered, for example at one of the above doses, once per 1, 2,3, 4, or 5 weeks, such as about once every 2 weeks. In some embodiments,administration of the anti-CSF1R antibody and the PD-1/PD-L1 inhibitorresults in a synergistic effect on tumor growth, weight, and/or volumecompared in a mouse xenograft model for squamous cell carcinoma comparedto administration of the anti-CSF1R antibody or PD-1/PD-L1 inhibitoralone.

In some embodiments of the methods, pancreatic cancer is treated withthe anti-CSF1R antibody (for instance, an anti-CSF1R antibody asdescribed herein, such as an antibody comprising the heavy and lightchain CDRs of HuAB1) and the PD-1/PD-L1 inhibitor (for instance, ananti-PD-1 antibody comprising the heavy chain and light chain CDRs ofnivolumab or pembrolizumab or a PD-1/PD-L1 inhibitor fusion protein orpeptide such as AMP-224 or AUR-012). In some embodiments, the patienthas documented localized or metastatic adenocarcinoma of the pancreas.In some embodiments, the patient may previously have received surgeryand/or radiation therapy. In some embodiments, the patient has not hadprior exposure to a PD-1/PD-L1 inhibitor, and in other embodiments, thepatient is refractory to PD-1/PD-L1 inhibitor treatment. In someembodiments, the anti-CSF1R antibody is administered at a dose of 0.1,0.3, 1, 2, 3, or 4 mg/kg. In some embodiments, the PD-1/PD-L1 inhibitoris administered at a dose of 0.5-10 mg/kg, such as, for example 1, 2, 3,4, or 5 mg/kg. In some embodiments, the anti-CSF1R antibody and thePD-1/PD-L1 inhibitor are administered, for example at one of the abovedoses, once per 1, 2, 3, 4, or 5 weeks, such as once every 2 weeks. Insome embodiments of the methods, colorectal cancer is treated with theanti-CSF1R antibody (for instance, an anti-CSF1R antibody as describedherein, such as an antibody comprising the heavy and light chain CDRs ofHuAB1) and the PD-1/PD-L1 inhibitor (for instance, an anti-PD-1 antibodycomprising the heavy chain and light chain CDRs of nivolumab orpembrolizumab or a PD-1/PD-L1 inhibitor fusion protein or peptide suchas AMP-224 or AUR-012). In some embodiments, the patient hasadenocarcinoma of the colon or rectum. In some embodiments, the patienthas metastatic colorectal cancer. In some embodiments, the patient hasmetastatic colorectal cancer despite prior treatment with one or more offluoropyrimidine, oxaliplatin, irinotecan, bevacizumab, cetuximab, orpanitumumab. In some embodiments, the patient has not had prior exposureto a PD-1/PD-L1 inhibitor, and in other embodiments, the patient isrefractory to PD-1/PD-L1 inhibitor treatment. In some embodiments, theanti-CSF1R antibody is administered at a dose of about 0.1, about 0.3,about 0.5, about 1, about 2, about 3, about 4, about 5 or about 10mg/kg. In some embodiments, the PD-1/PD-L1 inhibitor is administered ata dose of 0.1-10 mg/kg, such as, for example about 0.1, about 0.3, about0.5, about 1, about 2, about 3, about 4, about 5 or about 10 mg/kgmg/kg. In some embodiments, the anti-CSF1R antibody and the PD-1/PD-L1inhibitor are administered, for example at one of the above doses, onceper 1, 2, 3, 4, or 5 weeks, such as about once every 2 weeks. In someembodiments, administration of the anti-CSF1R antibody and thePD-1/PD-L1 inhibitor results in a synergistic effect on tumor growth,weight, and/or volume compared in a mouse xenograft model for pancreaticcancer (such as a model comprising KRas^(G12D)/Ink4a^(−/−) murinepancreatic ductal adenocarcinoma (PDAC) cells) compared toadministration of the anti-CSF1R antibody or PD-1/PD-L1 inhibitor alone.

In some embodiments of the methods, malignant glioma (e.g. glioblastomaor gliosarcoma) is treated with the anti-CSF1R antibody (for instance,an anti-CSF1R antibody as described herein, such as an antibodycomprising the heavy and light chain CDRs of HuAB1) and the PD-1/PD-L1inhibitor (for instance, an anti-PD-1 antibody comprising the heavychain and light chain CDRs of nivolumab or pembrolizumab or a PD-1/PD-L1inhibitor fusion protein or peptide such as AMP-224 or AUR-012). In someembodiments, the patient has previously been treated with surgery,radiotherapy, and/or temozolomide. In some embodiments, the patient hasGrade IV malignant glioma. In some embodiments, the patient has not hadprior exposure to a PD-1/PD-L1 inhibitor, and in other embodiments, thepatient is refractory to PD-1/PD-L1 inhibitor treatment. In someembodiments, the anti-CSF1R antibody is administered at a dose of about0.1, about 0.3, about 0.5, about 1, about 2, about 3, about 4, about 5or about 10 mg/kg. In some embodiments, the PD-1/PD-L1 inhibitor isadministered at a dose of 0.1-10 mg/kg, such as, for example about 0.1,about 0.3, about 0.5, about 1, about 2, about 3, about 4, about 5 orabout 10 mg/kg mg/kg. In some embodiments, the anti-CSF1R antibody andthe PD-1/PD-L1 inhibitor are administered, for example at one of theabove doses, once per 1, 2, 3, 4, or 5 weeks, such as about once every 2weeks. In some embodiments, administration of the anti-CSF1R antibodyand the PD-1/PD-L1 inhibitor results in a synergistic effect on tumorgrowth, weight, and/or volume compared in a mouse xenograft model forglioma compared to administration of the anti-CSF1R antibody orPD-1/PD-L1 inhibitor alone.

In some embodiments, the method further comprises administering one ormore additional anti-cancer agents. In certain embodiments, theanti-cancer agent is selected from the group consisting of an antibodyor antigen-binding portion thereof that binds specifically to CTLA-4(“anti-CTLA-4 antibody or antigen-binding portion thereof”) and inhibitsCTLA-4 activity, a chemotherapy, a platinum-based doublet chemotherapy,a tyrosine kinase inhibitor, an anti-VEGF inhibitor, anIndoleamine-pyrrole 2,3-dioxygenase (IDO) inhibitor, or any combinationthereof. In one embodiment, the anti-cancer agent is ipilimumab.

In some embodiments, compositions are provided, comprising an anti-CSF1Rantibody and a PD-1/PD-L1 inhibitor. In some embodiments, the PD-1/PD-L1inhibitor is an antibody. In some embodiments, the PD-1/PD-L1 inhibitoris an anti-PD-1 antibody. In some embodiments, the anti-PD-1 antibodycomprises the heavy chain and light chain CDRs of an antibody selectedfrom nivolumab and pembrolizumab. In some embodiments, the anti-PD-1antibody comprises the heavy chain and light chain variable regions ofan antibody selected from nivolumab and pembrolizumab. In someembodiments, the anti-PD-1 antibody is selected from nivolumab andpembrolizumab. In some embodiments, the PD-1/PD-L1 inhibitor is ananti-PD-L1 antibody. In some embodiments, the anti-PD-L1 antibodycomprises the heavy chain and light chain CDRs of an antibody selectedfrom BMS-936559, MPDL3280A, MEDI4736, and MSB0010718C. In someembodiments, the anti-PD-1 antibody comprises the heavy chain and lightchain variable regions of an antibody selected from BMS-936559,MPDL3280A, MEDI4736, and MSB0010718C. In some embodiments, the anti-PD-1antibody is selected from BMS-936559, MPDL3280A, MEDI4736, andMSB0010718C. In some embodiments, the PD-1/PD-L1 inhibitor is a fusionprotein. In some embodiments, the fusion protein is AMP-224.

In any of the compositions or methods described herein, the antibodyheavy chain and/or the antibody light chain of the anti-CSF1R antibodymay have the structure described below.

In any of the compositions or methods described herein, the anti-CSF1Rantibody heavy chain may comprise a sequence that is at least 90%, atleast 95%, at least 97%, at least 99%, or 100% identical to a sequenceselected from SEQ ID NOs: 9, 11, 13, and 39 to 45. In any of the methodsdescribed herein, the anti-CSF1R antibody light chain may comprise asequence that is at least 90%, at least 95%, at least 97%, at least 99%,or 100% identical to a sequence selected from SEQ ID NOs: 10, 12, 14,and 46 to 52. In any of the compositions or methods described herein,the anti-CSF1R antibody heavy chain may comprise a sequence that is atleast 90%, at least 95%, at least 97%, at least 99%, or 100% identicalto a sequence selected from SEQ ID NOs: 9, 11, 13, and 39 to 45, and theanti-CSF1R antibody light chain may comprise a sequence that is at least90%, at least 95%, at least 97%, at least 99%, or 100% identical to asequence selected from SEQ ID NOs: 10, 12, 14, and 46 to 52.

In any of the compositions or methods described herein, the anti-CSF1Rantibody HC CDR1, HC CDR2, and HC CDR3 may comprise a set of sequencesselected from: (a) SEQ ID NOs: 15, 16, and 17; (b) SEQ ID NOs: 21, 22,and 23; and (c) SEQ ID NOs: 27, 28, and 29. In any of the compositionsor methods described herein, the anti-CSF1R antibody LC CDR1, LC CDR2,and LC CDR3 may comprise a set of sequences selected from: (a) SEQ IDNOs: 18, 19, and 20; (b) SEQ ID NOs: 24, 25, and 26; and (c) SEQ ID NOs:30, 31, and 32.

In any of the compositions or methods described herein, the anti-CSF1Rantibody heavy chain may comprise an HC CDR1, HC CDR2, and HC CDR3,wherein the HC CDR1, HC CDR2, and HC CDR3 comprise a set of sequencesselected from: (a) SEQ ID NOs: 15, 16, and 17; (b) SEQ ID NOs: 21, 22,and 23; and (c) SEQ ID NOs: 27, 28, and 29; and the light chain maycomprise an LC CDR1, LC CDR2, and LC CDR3, wherein the LC CDR1, LC CDR2,and LC CDR3 comprise a set of sequences selected from: (a) SEQ ID NOs:18, 19, and 20; (b) SEQ ID NOs: 24, 25, and 26; and (c) SEQ ID NOs: 30,31, and 32.

In any of the compositions or methods described herein, the anti-CSF1Rantibody may comprise: (a) a heavy chain comprising a sequence that isat least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 9 and a light chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 10; (b) a heavychain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 11 and a light chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 12; (c) a heavy chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 13 and a light chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 14; (d) a heavychain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 39 and a light chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 46; (e) a heavy chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 40 and a light chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 46; (f) a heavychain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 41 and a light chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 46; (g) a heavy chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 39 and a light chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 47; (h) a heavychain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 40 and a light chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 47; (i) a heavy chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 41 and a light chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 47; and (j) aheavy chain comprising a sequence that is at least 95%, at least 97%, atleast 99%, or 100% identical to SEQ ID NO: 42 and a light chaincomprising a sequence that is at least 95%, at least 97%, at least 99%,or 100% identical to SEQ ID NO: 48; (k) a heavy chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 42 and a light chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 49; (l) a heavy chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 42 and a lightchain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 50; (m) a heavy chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 43 and a light chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 48; (n) a heavy chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 43 and a lightchain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 49; (o) a heavy chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 43 and a light chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 50; (p) a heavy chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 44 and a lightchain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 51; (q) a heavy chain comprising asequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 44 and a light chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 52; (r) a heavy chain comprising a sequence that is at least 95%, atleast 97%, at least 99%, or 100% identical to SEQ ID NO: 45 and a lightchain comprising a sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 51; or (s) a heavy chain comprisinga sequence that is at least 95%, at least 97%, at least 99%, or 100%identical to SEQ ID NO: 45 and a light chain comprising a sequence thatis at least 95%, at least 97%, at least 99%, or 100% identical to SEQ IDNO: 52.

In any of the compositions or methods described herein, the anti-CSF1Rantibody may comprise: (a) a heavy chain comprising a heavy chain (HC)CDR1 having the sequence of SEQ ID NO: 15, an HC CDR2 having thesequence of SEQ ID NO: 16, and an HC CDR3 having the sequence of SEQ IDNO: 17, and a light chain comprising a light chain (LC) CDR1 having thesequence of SEQ ID NO: 18, a LC CDR2 having the sequence of SEQ ID NO:19, and a LC CDR3 having the sequence of SEQ ID NO: 20; (b) a heavychain comprising a heavy chain (HC) CDR1 having the sequence of SEQ IDNO: 21, an HC CDR2 having the sequence of SEQ ID NO: 22, and an HC CDR3having the sequence of SEQ ID NO: 23, and a light chain comprising alight chain (LC) CDR1 having the sequence of SEQ ID NO: 24, a LC CDR2having the sequence of SEQ ID NO: 25, and a LC CDR3 having the sequenceof SEQ ID NO: 26; or (c) a heavy chain comprising a heavy chain (HC)CDR1 having the sequence of SEQ ID NO: 27, an HC CDR2 having thesequence of SEQ ID NO: 28, and an HC CDR3 having the sequence of SEQ IDNO: 29, and a light chain comprising a light chain (LC) CDR1 having thesequence of SEQ ID NO: 30, a LC CDR2 having the sequence of SEQ ID NO:31, and a LC CDR3 having the sequence of SEQ ID NO: 32.

In any of the compositions or methods described herein, the anti-CSF1Rantibody may comprise: (a) a heavy chain comprising a sequence of SEQ IDNO: 53 and a light chain comprising a sequence of SEQ ID NO: 60; (b) aheavy chain comprising a sequence of SEQ ID NO: 53 and a light chaincomprising a sequence of SEQ ID NO: 61; or (c) a heavy chain comprisinga sequence of SEQ ID NO: 58 and a light chain comprising a sequence ofSEQ ID NO: 65. In some embodiments, an antibody comprises a heavy chainand a light chain, wherein the antibody comprises: (a) a heavy chainconsisting of the sequence of SEQ ID NO: 53 and a light chain consistingof the sequence of SEQ ID NO: 60; (b) a heavy chain consisting of thesequence of SEQ ID NO: 53 and a light chain consisting of the sequenceof SEQ ID NO: 61; or (c) a heavy chain consisting of the sequence of SEQID NO: 58 and a light chain consisting of the sequence of SEQ ID NO: 65.

In any of the compositions or methods described herein, the anti-CSF1Rantibody may bind to human CSF1R and/or binds to cynomolgus CSF1R. Inany of the compositions or methods described herein, the anti-CSF1Rantibody may block ligand binding to CSF1R. In any of the compositionsor methods described herein, the anti-CSF1R antibody may block bindingof CSF1 and/or IL-34 to CSF1R. In any of the compositions or methodsdescribed herein, the anti-CSF1R antibody may block binding of both CSF1and IL-34 to CSF1R. In any of the compositions or methods describedherein, the anti-CSF1R antibody may inhibit ligand-induced CSF1Rphosphorylation. In any of the compositions or methods described herein,the anti-CSF1R antibody may inhibit CSF1- and/or IL-34-induced CSF1Rphosphorylation. In any of the compositions or methods described herein,the anti-CSF1R antibody may bind to human CSF1R with an affinity (K_(D))of less than 1 nM. In any of the compositions or methods describedherein, the anti-CSF1R antibody may inhibit monocyte proliferationand/or survival responses in the presence of CSF1 or IL-34.

In any of the compositions or methods described herein, the PD-1/PD-L1inhibitor may be an antibody, such as an anti-PD-1 antibody, with astructure described below.

In any of the compositions or methods described herein, the PD-1/PD-L1inhibitor may be an antibody with an antibody heavy chain may comprisinga sequence that is at least 90%, at least 95%, at least 97%, at least99%, or 100% identical to a sequence selected from SEQ ID NOs: 100 and101. In any of the methods described herein, the PD-1/PD-L1 inhibitormay be an antibody with an antibody light chain comprising a sequencethat is at least 90%, at least 95%, at least 97%, at least 99%, or 100%identical to a sequence selected from SEQ ID NOs: 102 and 103.

In any of the compositions or methods described herein, the PD-1/PD-L1inhibitor may be an antibody with heavy chain (HC) CDR1, HC CDR2, and HCCDR3 comprising a set of sequences selected from SEQ ID NOs: 105, 107,and 109. In any of the compositions or methods described herein, thePD-1/PD-L1 inhibitor may be an antibody with light chain (LC) CDR1, LCCDR2, and LC CDR3 may comprise a set of sequences selected from SEQ IDNOs: 112, 114, and 116.

In any of the compositions or methods described herein, the PD-1/PD-L1inhibitor may be an antibody comprising: (a) a heavy chain comprising avariable region sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 100 and a light chain comprising avariable region sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 102; (b) a heavy chain comprising aconstant region sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 101 and a light chain comprising aconstant region sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 103; (c) a heavy chain comprising avariable region sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 100 and a light chain comprising avariable region sequence that is at least 95%, at least 97%, at least99%, or 100% identical to SEQ ID NO: 102; and/or (d) a heavy chaincomprising a constant region sequence that is at least 95%, at least97%, at least 99%, or 100% identical to SEQ ID NO: 101 and a light chaincomprising a constant region sequence that is at least 95%, at least97%, at least 99%, or 100% identical to SEQ ID NO: 103.

In any of the compositions or methods described herein, the PD-1/PD-L1inhibitor may be an antibody comprising: a heavy chain comprising aheavy chain (HC) CDR1 having the sequence of SEQ ID NO: 105, an HC CDR2having the sequence of SEQ ID NO: 107, and an HC CDR3 having thesequence of SEQ ID NO: 109, and a light chain comprising a light chain(LC) CDR1 having the sequence of SEQ ID NO: 112, a LC CDR2 having thesequence of SEQ ID NO: 114, and a LC CDR3 having the sequence of SEQ IDNO: 116. In any of the compositions or methods described herein, thePD-1/PD-L1 inhibitor may be an antibody comprising: a heavy chaincomprising a heavy chain (HC) FR1 having the sequence of SEQ ID NO: 104,an HC FR2 having the sequence of SEQ ID NO: 106, an HC FR3 having thesequence of SEQ ID NO: 108, and an HC FR4 having the sequence of SEQ IDNO: 110; and/or, a light chain comprising a light chain (LC) FR1 havingthe sequence of SEQ ID NO: 111, a LC FR2 having the sequence of SEQ IDNO: 113, a LC FR3 having the sequence of SEQ ID NO: 115, and a LC FR4having the sequence of SEQ ID NO: 117.

In any of the compositions or methods described herein, the anti-CSF1Rantibody or PD-1/PD-L1 inhibitor may be a humanized or chimericantibody. In any of the compositions or methods described herein, theanti-CSF1R or PD-1/PD-L1 inhibitor may be selected from a Fab, an Fv, anscFv, a Fab′, and a (Fab′)₂. In any of the compositions or methodsdescribed herein, the anti-CSF1R or PD-1/PD-L1 inhibitor may be selectedfrom an IgA, an IgG, and an IgD. In any of the compositions or methodsdescribed herein, the anti-CSF1R antibody or PD-1/PD-L1 inhibitor may bean IgG. In any of the methods described herein, the antibody may be anIgG1, IgG2 or IgG4.

In any of the methods described herein, the tumor may or may not expressPD-L1. In some embodiments, the tumor is PD-L1 positive. In otherembodiments, the tumor is PD-L1 negative. In any of the methodsdescribed herein, the tumor may or may not express PD-L2. In someembodiments, the tumor is PD-L2 positive. In other embodiments, thetumor is PD-L2 negative.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1A-C show an alignment of the humanized heavy chain variableregions for each of humanized antibodies huAb1 to huAb16, as discussedin Example 1. Boxed residues are amino acids in the human acceptorsequence that were changed back to the corresponding mouse residue.

FIG. 2A-C show an alignment of the humanized light chain variableregions for each of humanized antibodies huAb1 to huAb16, as discussedin Example 1. Boxed amino acids are residues in the human acceptorsequence that were changed back to the corresponding mouse residue.

FIG. 3 is a heat map showing the correlation between CSF1R expressionand Tregs, PD-L1/PD-1 expression, and CD8+ T cells in various cancers.

FIG. 4A shows mean change in tumor volume over time in C57BL/6 miceinoculated subcutaneously with MC38 colorectal carcinoma cells and dosedwith an anti-CSF1R antibody, an anti-PD-1 antibody, or a combination ofboth antibodies, or with an IgG control. Both anti-CSF1R or anti-PD-1treatment reduced the growth rate of MC38 compared to the control. Thecombination of anti-CSF1R and anti-PD-1 suppressed MC38 growth greaterthan either treatment alone (P<0.05). FIG. 4B shows individual MC38tumor volumes as assessed on day 11 after initiation of treatment(p-values shown on figure). Statistical significance was determined viatwo-tailed, unpaired t-Test.

FIG. 5 shows mean tumor weight in C57BL/6 mice inoculated surgicallywith KRas^(G12D)/Ink4a^(−/−) murine pancreatic ductal adenocarincoma(PDAC) cells colorectal carcinoma cells and dosed with an anti-CSF1Rantibody (lanes marked “008”), an anti-PD-1 antibody, or a combinationof both antibodies, together with gemcitabine (GEM). Treatment witheither anti-CSF1R or anti-PD-1 reduced tumor burden compared to controlmice. The combination of anti-CSF1R, anti-PD-1, and GEM significantlyreduced tumor burden compared to either anti-CSF1R and GEM or anti-PD-1and GEM (p-values shown on figure). Statistical significance wasdetermined via two-tailed, unpaired t-Test.

FIG. 6 is a description of the treatment cohorts for the clinicalexperiments described in Examples 7 and 8 involving huAB1 (also calledFPA008) and nivolumab.

FIG. 7 shows dose escalation criteria for the clinical experiments ofExamples 7 and 8.

FIG. 8 shows that treatment with an anti-CSF1R antibody (calledcmFPA008) increases the frequency of cytotoxic T cells and expression ofPD-L1 and other genes in two colorectal mouse tumor models.Immunocompetent mice were inoculated subcutaneously with MC38 (top) orCT26 (bottom) colorectal carcinoma cells and dosed with cmFPA008 ormouse IgG1 as a control. Gene expression was assessed in tumor samples(n≥7 per group) and normalized to multiple housekeeping genes.Expression values shown are relative to the IgG control. Statisticalsignificance was determined via two-tailed, unpaired t-Test (* p<0.05,** p<0.01).

DETAILED DESCRIPTION

Tumor-associated macrophages (TAMs) are implicated in the pathogenesisof many cancers, and correlate with poor prognosis. Inhibition of CSF1Rcan reduce immunosuppressive TAMs in mouse models and human tumors. See,e.g., Ries et al., 2014, Cancer Cell, 25: 846-859; Pyontech et al.,2013, Nature Med., 19: 1264-1272; and Zhu et al., 2014, Cancer Res., 74:5057-5069. Small molecule inhibition of CSF1R synergizes with immunecheckpoint blockade in a pancreatic tumor model. See Zhu et al., 2014,Cancer Res., 74: 5057-5069. While not intending to be bound by anyparticular theory, the present invention is directed to methods oftreating tumors that may have both CSF1R-expressing TAMs andPD-1-expressing CD8+ T cells and will be sensitive to combinationtherapy with an anti-CSF1R antibody and a PD-1/PD-L1 inhibitor. In someinstances, tumors that have both CSF1R-expressing TAMs andPD-1-expressing CD8+ T cells may be resistant to PD-1/PD-L1 monotherapy,but should be sensitive to the combination therapy. Through expressionanalysis, the present inventors have identified certain tumor types thathave both CSF1R-expressing TAMs and PD-1-expressing CD8+ T cells,including, but not limited to, bladder cancer, cervical cancer (such assquamous cell cervical cancer), head and neck squamous cell carcinoma(SCCHN), rectal adenocarcinoma, non-small cell lung cancer (NSCLC),endometrial cancer, prostate adenocarcinoma, colon cancer, ovariancancer (such as serous epithelial ovarian cancer), and melanoma.Similarly, without intending to be bound by any particular theory,tumors that have high levels of CSF1R-expressing TAMs, which aresuppressing PD-1-expressing CD8+ T cells may be sensitive to combinationtherapy, for example, because inhibition of TAMs with an anti-CSF1Rantibody may boost PD-1 expressing CD8+ T cells, rendering the tumorsensitive to a PD-1/PD-L1 inhibitor.

Accordingly, the present invention provides methods of treating cancercomprising administering an anti-CSF1R antibody and a PD-1/PD-L1inhibitor. In some embodiments, a PD-1/PD-L1 inhibitor is an antibody.In some embodiments, a PD-1/PD-L1 inhibitor is an antibody that inhibitsPD-1. In some such embodiments, the anti-PD-1 antibody disrupts PD-L1binding to PD-1. In some embodiments, a PD-1/PD-L1 inhibitor is anantibody that binds to PD-L1. In some such embodiments, the anti-PD-L1antibody disrupts PD-L1 binding to PD-1. In some embodiments, aPD-1/PD-L1 inhibitor is a fusion protein that disrupts PD-L1 binding toPD-1, such as AMP-224. In some embodiments, a PD-1/PD-L1 inhibitor is apeptide that disrupts PD-L1 binding to PD-1, such as AUR-012.

As noted above, in certain embodiments, the PD-1/PD-L1 inhibitor is ananti-PD-L1 antibody. In some embodiments, an anti-PD-L1 Ab can besubstituted for the anti-PD-1 Ab in any of the therapeutic methods orcompositions disclosed herein. In certain embodiments, the anti-PD-L1 Abis BMS-936559 (formerly 12A4 or MDX-1105) (see, e.g., U.S. Pat. No.7,943,743; WO 2013/173223). In other embodiments, the anti-PD-L1 Ab isMPDL3280A (also known as RG7446) (see, e.g., Herbst; U.S. Pat. No.8,217,149) or MEDI4736 (Khleif, 2013).

The section headings used herein are for organizational purposes onlyand are not to be construed as limiting the subject matter described.All references cited herein, including patent applications andpublications, are incorporated herein by reference in their entiretiesfor any purpose.

Definitions

Unless otherwise defined, scientific and technical terms used inconnection with the present invention shall have the meanings that arecommonly understood by those of ordinary skill in the art. Further,unless otherwise required by context, singular terms shall includepluralities and plural terms shall include the singular.

Exemplary techniques used in connection with recombinant DNA,oligonucleotide synthesis, tissue culture and transformation (e.g.,electroporation, lipofection), enzymatic reactions, and purificationtechniques are known in the art. Many such techniques and procedures aredescribed, e.g., in Sambrook et al. Molecular Cloning: A LaboratoryManual (2nd ed., Cold Spring Harbor Laboratory Press, Cold SpringHarbor, N.Y. (1989)), among other places. In addition, exemplarytechniques for chemical syntheses, chemical analyses, pharmaceuticalpreparation, formulation, and delivery, and treatment of patients arealso known in the art.

In this application, the use of “or” means “and/or” unless statedotherwise. In the context of a multiple dependent claim, the use of “or”refers back to more than one preceding independent or dependent claim inthe alternative only. Also, terms such as “element” or “component”encompass both elements and components comprising one unit and elementsand components that comprise more than one subunit unless specificallystated otherwise.

As described herein, any concentration range, percentage range, ratiorange or integer range is to be understood to include the value of anyinteger within the recited range and, when appropriate, fractionsthereof (such as one tenth and one hundredth of an integer), unlessotherwise indicated.

Units, prefixes, and symbols are denoted in their Systeme Internationalde Unites (SI) accepted form. Numeric ranges are inclusive of thenumbers defining the range. The headings provided herein are notlimitations of the various aspects of the disclosure, which can be hadby reference to the specification as a whole. Accordingly, the termsdefined immediately below are more fully defined by reference to thespecification in its entirety.

As utilized in accordance with the present disclosure, the followingterms, unless otherwise indicated, shall be understood to have thefollowing meanings:

“Administering” refers to the physical introduction of a compositioncomprising a therapeutic agent to a subject, using any of the variousmethods and delivery systems known to those skilled in the art. Routesof administration for the anti-PD-1 Ab and/or the anti-PD-L1 Ab includeintravenous, intramuscular, subcutaneous, intraperitoneal, spinal orother parenteral routes of administration, for example by injection orinfusion. The phrase “parenteral administration” as used herein meansmodes of administration other than enteral and topical administration,usually by injection, and includes, without limitation, intravenous,intramuscular, intraarterial, intrathecal, intralymphatic,intralesional, intracapsular, intraorbital, intracardiac, intradermal,intraperitoneal, transtracheal, subcutaneous, subcuticular,intraarticular, subcapsular, subarachnoid, intraspinal, epidural andintrasternal injection and infusion, as well as in vivo electroporation.Non-parenteral routes include a topical, epidermal or mucosal route ofadministration, for example, orally, intranasally, vaginally, rectally,sublingually or topically. Administering can also be performed, forexample, once, a plurality of times, and/or over one or more extendedperiods.

An “adverse event” (AE) as used herein is any unfavorable and generallyunintended or undesirable sign (including an abnormal laboratoryfinding), symptom, or disease associated with the use of a medicaltreatment. For example, an adverse event can be associated withactivation of the immune system or expansion of immune system cells(e.g., T cells) in response to a treatment. A medical treatment can haveone or more associated AEs and each AE can have the same or differentlevel of severity. Reference to methods capable of “altering adverseevents” means a treatment regime that decreases the incidence and/orseverity of one or more AEs associated with the use of a differenttreatment regime. The terms “nucleic acid molecule” and “polynucleotide”may be used interchangeably, and refer to a polymer of nucleotides. Suchpolymers of nucleotides may contain natural and/or non-naturalnucleotides, and include, but are not limited to, DNA, RNA, and PNA.“Nucleic acid sequence” refers to the linear sequence of nucleotidesthat comprise the nucleic acid molecule or polynucleotide.

The terms “polypeptide” and “protein” are used interchangeably to referto a polymer of amino acid residues, and are not limited to a minimumlength. Such polymers of amino acid residues may contain natural ornon-natural amino acid residues, and include, but are not limited to,peptides, oligopeptides, dimers, trimers, and multimers of amino acidresidues. Both full-length proteins and fragments thereof areencompassed by the definition. The terms also include post-expressionmodifications of the polypeptide, for example, glycosylation,sialylation, acetylation, phosphorylation, and the like. Furthermore,for purposes of the present invention, a “polypeptide” refers to aprotein which includes modifications, such as deletions, additions, andsubstitutions (generally conservative in nature), to the nativesequence, as long as the protein maintains the desired activity. Thesemodifications may be deliberate, as through site-directed mutagenesis,or may be accidental, such as through mutations of hosts which producethe proteins or errors due to PCR amplification.

The term “CSF1R” refers herein to the full-length CSF1R, which includesthe N-terminal ECD, the transmembrane domain, and the intracellulartyrosine kinase domain, with or without an N-terminal leader sequence.In some embodiments, the CSF1R is a human CSF1R having the amino acidsequence of SEQ ID NO: 1 or SEQ ID NO: 2.

The terms “programmed cell death protein 1” and “PD-1” refer to animmunoinhibitory receptor belonging to the CD28 family. PD-1 isexpressed predominantly on previously activated T cells in vivo, andbinds to two ligands, PD-L1 and PD-L2. The term “PD-1” as used hereinincludes human PD-1 (hPD-1), variants, isoforms, and species homologs ofhPD-1, and analogs having at least one common epitope with hPD-1. Thecomplete hPD-1 sequence can be found under GenBank Accession No. U64863.In some embodiments, the PD-1 is a human PD-1 having the amino acidsequence of SEQ ID NO: 96 (precursor, with signal sequence) or SEQ IDNO: 97 (mature, without signal sequence).

The terms “programmed cell death 1 ligand 1” and “PD-L1” (PD-L1; B7homolog-1; B7-H1; or CD274) and “Programmed Death Ligand-2” (PD-L2;B7-DC; or CD273) are two cell surface glycoprotein ligands for PD-1 thatdownregulate T-cell activation and cytokine secretion upon binding toPD-1. The term “PD-L1” as used herein includes human PD-L1 (hPD-L1),variants, isoforms, and species homologs of hPD-L1, and analogs havingat least one common epitope with hPD-L1. The complete hPD-L1 sequencecan be found under GenBank Accession No. Q9NZQ7. In some embodiments,the PD-L1 is a human PD-L1 having the amino acid sequence of SEQ ID NO:98 (precursor, with signal sequence) or SEQ ID NO: 99 (mature, withoutsignal sequence).

“Cytotoxic T-Lymphocyte Antigen-4” (CTLA-4) refers to animmunoinhibitory receptor belonging to the CD28 family. CTLA-4 isexpressed exclusively on T cells in vivo, and binds to two ligands, CD80and CD86 (also called B7-1 and B7-2, respectively). The term “CTLA-4” asused herein includes human CTLA-4 (hCTLA-4), variants, isoforms, andspecies homologs of hCTLA-4, and analogs having at least one commonepitope with hCTLA-4. The complete hCTLA-4 sequence can be found underGenBank Accession No. AAB59385.

The term “PD-1/PD-L1 inhibitor” refers to a moiety that disrupts thePD-1/PD-L1 signaling pathway. In some embodiments, the inhibitorinhibits the PD-1/PD-L1 signaling pathway by binding to PD-1 and/orPD-L1. In some embodiments, the inhibitor also binds to PD-L2. In someembodiments, a PD-1/PD-L1 inhibitor blocks binding of PD-1 to PD-L1and/or PD-L2. Nonlimiting exemplary PD-1/PD-L1 inhibitors includeantibodies that bind to PD-1); antibodies that bind to PD-L1; fusionproteins, such as AMP-224; and peptides, such as AUR-012.

The term “antibody that inhibits PD-1” refers to an antibody that bindsto PD-1 or binds to PD-L1 and thereby inhibits PD-1 and/or PD-L1signaling. In some embodiments, an antibody that inhibits PD-1 binds toPD-1 and blocks binding of PD-L1 and/or PD-L2 to PD-1. In someembodiments, an antibody that inhibits PD-1 binds to PD-L1 and blocksbinding of PD-1 to PD-L1. An antibody that inhibits PD-1 that binds toPD-L1 may be referred to as an anti-PD-L1 antibody. An antibody thatinhibits PD-1 that binds to PD-1 may be referred to as an anti-PD-1antibody.

“PD-L1 positive” as used herein can be interchangeably used with “PD-L1expression of at least about 5%.” PD-L1 expression can be measured byany methods known in the art. In some embodiments, the PD-L1 expressionis measured by an automated IHC. A PD-L1 positive tumor can thus have atleast about 5%, at least about 10%, or at least about 20% of tumor cellsexpressing PD-L1 as measured by an automated IHC. In certainembodiments, “PD-L1 positive” means that there are at least 100 cellsthat express PD-L1 on the surface of the cells.

“PD-L2 positive” as used herein can be interchangeably used with “PD-L2expression of at least about 5%.” PD-L2 expression can be measured byany methods known in the art. In some embodiments, the PD-L2 expressionis measured by an automated IHC. A PD-L2 positive tumor can thus have atleast about 5%, at least about 10%, or at least about 20% of tumor cellsexpressing PD-L2 as measured by an automated IHC. In certainembodiments, “PD-L2 positive” means that there are at least 100 cellsthat express PD-L2 on the surface of the cells.

With reference to anti-CSF1R antibodies the term “blocks binding of” aligand, such as CSF1 and/or IL-34, and grammatical variants thereof, areused to refer to the ability to inhibit the interaction between CSF1Rand a CSF1R ligand, such as CSF1 and/or IL-34. Such inhibition may occurthrough any mechanism, including direct interference with ligandbinding, e.g., because of overlapping binding sites on CSF1R, and/orconformational changes in CSF1R induced by the antibody that alterligand affinity, etc. Antibodies and antibody fragments referred to as“functional” are characterized by having such properties.

With reference to anti-PD-1 antibodies the term “blocks binding of” aligand, such as PD-L1, and grammatical variants thereof, are used torefer to the ability to inhibit the interaction between PD-1 and a PD-1ligand, such as PD-L1. Such inhibition may occur through any mechanism,including direct interference with ligand binding, e.g., because ofoverlapping binding sites on PD-1, and/or conformational changes in PD-1induced by the antibody that alter ligand affinity, etc. Antibodies andantibody fragments referred to as “functional” are characterized byhaving such properties.

With reference to anti-PD-L1 antibodies the term “blocks binding of” aligand, such as PD-1, and grammatical variants thereof, are used torefer to the ability to inhibit the interaction between PD-L1 and aPD-L1 ligand, such as PD-1. Such inhibition may occur through anymechanism, including direct interference with ligand binding, e.g.,because of overlapping binding sites on PD-L1, and/or conformationalchanges in PD-L1 induced by the antibody that alter ligand affinity,etc. Antibodies and antibody fragments referred to as “functional” arecharacterized by having such properties.

The term “antibody” as used herein refers to a molecule comprising atleast complementarity-determining region (CDR) 1, CDR2, and CDR3 of aheavy chain and at least CDR1, CDR2, and CDR3 of a light chain, whereinthe molecule is capable of binding to antigen. The term antibodyincludes, but is not limited to, fragments that are capable of bindingantigen, such as Fv, single-chain Fv (scFv), Fab, Fab′, and (Fab′)₂. Theterm antibody also includes, but is not limited to, chimeric antibodies,humanized antibodies, and antibodies of various species such as mouse,human, cynomolgus monkey, etc.

In some embodiments, an antibody comprises a heavy chain variable regionand a light chain variable region. In some embodiments, an antibodycomprises at least one heavy chain comprising a heavy chain variableregion and at least a portion of a heavy chain constant region, and atleast one light chain comprising a light chain variable region and atleast a portion of a light chain constant region. In some embodiments,an antibody comprises two heavy chains, wherein each heavy chaincomprises a heavy chain variable region and at least a portion of aheavy chain constant region, and two light chains, wherein each lightchain comprises a light chain variable region and at least a portion ofa light chain constant region. As used herein, a single-chain Fv (scFv),or any other antibody that comprises, for example, a single polypeptidechain comprising all six CDRs (three heavy chain CDRs and three lightchain CDRs) is considered to have a heavy chain and a light chain. Insome such embodiments, the heavy chain is the region of the antibodythat comprises the three heavy chain CDRs and the light chain in theregion of the antibody that comprises the three light chain CDRs.

The term “heavy chain variable region” as used herein refers to a regioncomprising heavy chain CDR1, framework (FR) 2, CDR2, FR3, and CDR3. Insome embodiments, a heavy chain variable region also comprises at leasta portion of an FR1 and/or at least a portion of an FR4. In someembodiments, a heavy chain CDR1 corresponds to Kabat residues 26 to 35;a heavy chain CDR2 corresponds to Kabat residues 50 to 65; and a heavychain CDR3 corresponds to Kabat residues 95 to 102. See, e.g., KabatSequences of Proteins of Immunological Interest (1987 and 1991, NIH,Bethesda, Md.); and FIG. 1. In some embodiments, a heavy chain CDR1corresponds to Kabat residues 31 to 35; a heavy chain CDR2 correspondsto Kabat residues 50 to 65; and a heavy chain CDR3 corresponds to Kabatresidues 95 to 102. See id.

The term “heavy chain constant region” as used herein refers to a regioncomprising at least three heavy chain constant domains, C_(H)1, C_(H)2,and C_(H)3. Nonlimiting exemplary heavy chain constant regions includeγ, δ, and α. Nonlimiting exemplary heavy chain constant regions alsoinclude ε and μ. Each heavy constant region corresponds to an antibodyisotype. For example, an antibody comprising a γ constant region is anIgG antibody, an antibody comprising a δ constant region is an IgDantibody, and an antibody comprising an α constant region is an IgAantibody. Further, an antibody comprising a μ constant region is an IgMantibody, and an antibody comprising an c constant region is an IgEantibody. Certain isotypes can be further subdivided into subclasses.For example, IgG antibodies include, but are not limited to, IgG1(comprising a γ₁ constant region), IgG2 (comprising a γ₂ constantregion), IgG3 (comprising a γ₃ constant region), and IgG4 (comprising aγ₄ constant region) antibodies; IgA antibodies include, but are notlimited to, IgA1 (comprising an α₁ constant region) and IgA2 (comprisingan α₂ constant region) antibodies; and IgM antibodies include, but arenot limited to, IgM1 and IgM2.

In some embodiments, a heavy chain constant region comprises one or moremutations (or substitutions), additions, or deletions that confer adesired characteristic on the antibody. A nonlimiting exemplary mutationis the S241P mutation in the IgG4 hinge region (between constant domainsC_(H)1 and C_(H)2), which alters the IgG4 motif CPSCP to CPPCP, which issimilar to the corresponding motif in IgG1. That mutation, in someembodiments, results in a more stable IgG4 antibody. See, e.g., Angal etal., Mol. Immunol. 30: 105-108 (1993); Bloom et al., Prot. Sci. 6:407-415 (1997); Schuurman et al., Mol. Immunol. 38: 1-8 (2001).

The term “heavy chain” (abbreviated HC) as used herein refers to apolypeptide comprising at least a heavy chain variable region, with orwithout a leader sequence. In some embodiments, a heavy chain comprisesat least a portion of a heavy chain constant region. The term“full-length heavy chain” as used herein refers to a polypeptidecomprising a heavy chain variable region and a heavy chain constantregion, with or without a leader sequence.

The term “light chain variable region” as used herein refers to a regioncomprising light chain CDR1, framework (FR) 2, CDR2, FR3, and CDR3. Insome embodiments, a light chain variable region also comprises an FR1and/or an FR4. In some embodiments, a light chain CDR1 corresponds toKabat residues 24 to 34; a light chain CDR2 corresponds to Kabatresidues 50 to 56; and a light chain CDR3 corresponds to Kabat residues89 to 97. See, e.g., Kabat Sequences of Proteins of ImmunologicalInterest (1987 and 1991, NIH, Bethesda, Md.); and FIG. 1.

The term “light chain constant region” as used herein refers to a regioncomprising a light chain constant domain, C_(L). Nonlimiting exemplarylight chain constant regions include λ and κ.

The term “light chain” (abbreviate LC) as used herein refers to apolypeptide comprising at least a light chain variable region, with orwithout a leader sequence. In some embodiments, a light chain comprisesat least a portion of a light chain constant region. The term“full-length light chain” as used herein refers to a polypeptidecomprising a light chain variable region and a light chain constantregion, with or without a leader sequence.

A “chimeric antibody” as used herein refers to an antibody comprising atleast one variable region from a first species (such as mouse, rat,cynomolgus monkey, etc.) and at least one constant region from a secondspecies (such as human, cynomolgus monkey, etc.). In some embodiments, achimeric antibody comprises at least one mouse variable region and atleast one human constant region. In some embodiments, a chimericantibody comprises at least one cynomolgus variable region and at leastone human constant region. In some embodiments, a chimeric antibodycomprises at least one rat variable region and at least one mouseconstant region. In some embodiments, all of the variable regions of achimeric antibody are from a first species and all of the constantregions of the chimeric antibody are from a second species.

A “humanized antibody” as used herein refers to an antibody in which atleast one amino acid in a framework region of a non-human variableregion has been replaced with the corresponding amino acid from a humanvariable region. In some embodiments, a humanized antibody comprises atleast one human constant region or fragment thereof. In someembodiments, a humanized antibody is a Fab, an scFv, a (Fab′)₂, etc.

A “CDR-grafted antibody” as used herein refers to a humanized antibodyin which the complementarity determining regions (CDRs) of a first(non-human) species have been grafted onto the framework regions (FRs)of a second (human) species.

A “human antibody” as used herein refers to antibodies produced inhumans, antibodies produced in non-human animals that comprise humanimmunoglobulin genes, such as XenoMouse®, and antibodies selected usingin vitro methods, such as phage display, wherein the antibody repertoireis based on a human immunoglobulin sequences.

An “anti-antigen” Ab refers to an Ab that binds specifically to theantigen. For example, an anti-PD-1 Ab binds specifically to PD-1, ananti-PD-L1 Ab binds specifically to PD-L1, and an anti-CTLA-4 Ab bindsspecifically to CTLA-4.

The term “leader sequence” refers to a sequence of amino acid residueslocated at the N terminus of a polypeptide that facilitates secretion ofa polypeptide from a mammalian cell. A leader sequence may be cleavedupon export of the polypeptide from the mammalian cell, forming a matureprotein. Leader sequences may be natural or synthetic, and they may beheterologous or homologous to the protein to which they are attached.Exemplary leader sequences include, but are not limited to, antibodyleader sequences, such as, for example, the amino acid sequences of SEQID NOs: 3 and 4, which correspond to human light and heavy chain leadersequences, respectively. Nonlimiting exemplary leader sequences alsoinclude leader sequences from heterologous proteins. In someembodiments, an antibody lacks a leader sequence. In some embodiments,an antibody comprises at least one leader sequence, which may beselected from native antibody leader sequences and heterologous leadersequences.

The term “vector” is used to describe a polynucleotide that may beengineered to contain a cloned polynucleotide or polynucleotides thatmay be propagated in a host cell. A vector may include one or more ofthe following elements: an origin of replication, one or more regulatorysequences (such as, for example, promoters and/or enhancers) thatregulate the expression of the polypeptide of interest, and/or one ormore selectable marker genes (such as, for example, antibioticresistance genes and genes that may be used in colorimetric assays,e.g., β-galactosidase). The term “expression vector” refers to a vectorthat is used to express a polypeptide of interest in a host cell.

A “host cell” refers to a cell that may be or has been a recipient of avector or isolated polynucleotide. Host cells may be prokaryotic cellsor eukaryotic cells. Exemplary eukaryotic cells include mammalian cells,such as primate or non-primate animal cells; fungal cells, such asyeast; plant cells; and insect cells. Nonlimiting exemplary mammaliancells include, but are not limited to, NSO cells, PER.C6® cells(Crucell), and 293 and CHO cells, and their derivatives, such as 293-6Eand DG44 cells, respectively.

The term “isolated” as used herein refers to a molecule that has beenseparated from at least some of the components with which it istypically found in nature. For example, a polypeptide is referred to as“isolated” when it is separated from at least some of the components ofthe cell in which it was produced. Where a polypeptide is secreted by acell after expression, physically separating the supernatant containingthe polypeptide from the cell that produced it is considered to be“isolating” the polypeptide. Similarly, a polynucleotide is referred toas “isolated” when it is not part of the larger polynucleotide (such as,for example, genomic DNA or mitochondrial DNA, in the case of a DNApolynucleotide) in which it is typically found in nature, or isseparated from at least some of the components of the cell in which itwas produced, e.g., in the case of an RNA polynucleotide. Thus, a DNApolynucleotide that is contained in a vector inside a host cell may bereferred to as “isolated” so long as that polynucleotide is not found inthat vector in nature.

The term “elevated level” means a higher level of a protein in aparticular tissue of a subject relative to the same tissue in a control,such as an individual or individuals who are not suffering from canceror other condition described herein. The elevated level may be theresult of any mechanism, such as increased expression, increasedstability, decreased degradation, increased secretion, decreasedclearance, etc., of the protein.

The term “reduce” or “reduces” means to lower the level of a protein ina particular tissue of a subject by at least 10%. In some embodiments,an agent, such as an antibody that binds CSF1R or a PD-1/PD-L1inhibitor, reduces the level of a protein in a particular tissue of asubject by at least 15%, at least 20%, at least 25%, at least 30%, atleast 35%, at least 40%, at least 45%, at least 50%, at least 55%, atleast 60%, at least 65%, at least 70%, at least 75%, at least 80%, atleast 85%, or at least 90%. In some embodiments, the level of a proteinis reduced relative to the level of the protein prior to contacting withan agent, such as an antibody that binds CSF1R or a PD-1/PD-L1inhibitor.

The term “resistant,” when used in the context of resistance to atherapeutic agent, means a decreased response or lack of response to astandard dose of the therapeutic agent, relative to the subject'sresponse to the standard dose of the therapeutic agent in the past, orrelative to the expected response of a similar subject with a similardisorder to the standard dose of the therapeutic agent. Thus, in someembodiments, a subject may be resistant to therapeutic agent althoughthe subject has not previously been given the therapeutic agent, or thesubject may develop resistance to the therapeutic agent after havingresponded to the agent on one or more previous occasions.

The terms “subject” and “patient” are used interchangeably herein torefer to a human. In some embodiments, methods of treating othermammals, including, but not limited to, rodents, simians, felines,canines, equines, bovines, porcines, ovines, caprines, mammalianlaboratory animals, mammalian farm animals, mammalian sport animals, andmammalian pets, are also provided.

The term “sample,” as used herein, refers to a composition that isobtained or derived from a subject that contains a cellular and/or othermolecular entity that is to be characterized, quantitated, and/oridentified, for example based on physical, biochemical, chemical and/orphysiological characteristics. An exemplary sample is a tissue sample.

The term “tissue sample” refers to a collection of similar cellsobtained from a tissue of a subject. The source of the tissue sample maybe solid tissue as from a fresh, frozen and/or preserved organ or tissuesample or biopsy or aspirate; blood or any blood constituents; bodilyfluids such as cerebral spinal fluid, amniotic fluid, peritoneal fluid,synovial fluid, or interstitial fluid; cells from any time in gestationor development of the subject. In some embodiments, a tissue sample is asynovial biopsy tissue sample and/or a synovial fluid sample. In someembodiments, a tissue sample is a synovial fluid sample. The tissuesample may also be primary or cultured cells or cell lines. Optionally,the tissue sample is obtained from a disease tissue/organ. The tissuesample may contain compounds that are not naturally intermixed with thetissue in nature such as preservatives, anticoagulants, buffers,fixatives, nutrients, antibiotics, or the like. A “control sample” or“control tissue”, as used herein, refers to a sample, cell, or tissueobtained from a source known, or believed, not to be afflicted with thedisease for which the subject is being treated.

For the purposes herein a “section” of a tissue sample means a part orpiece of a tissue sample, such as a thin slice of tissue or cells cutfrom a solid tissue sample.

The term “cancer” is used herein to refer to a group of cells thatexhibit abnormally high levels of proliferation and growth. A cancer maybe benign (also referred to as a benign tumor), pre-malignant, ormalignant. Cancer cells may be solid cancer cells or leukemic cancercells. The term “cancer growth” is used herein to refer to proliferationor growth by a cell or cells that comprise a cancer that leads to acorresponding increase in the size or extent of the cancer.

Examples of cancer include but are not limited to, carcinoma, lymphoma,blastoma, sarcoma, and leukemia. More particular nonlimiting examples ofsuch cancers include squamous cell cancer, small-cell lung cancer,pituitary cancer, esophageal cancer, astrocytoma, soft tissue sarcoma,non-small cell lung cancer (including squamous cell non-small cell lungcancer), adenocarcinoma of the lung, squamous carcinoma of the lung,cancer of the peritoneum, hepatocellular cancer, gastrointestinalcancer, pancreatic cancer, glioblastoma, cervical cancer, ovariancancer, liver cancer, bladder cancer, hepatoma, breast cancer, coloncancer, colorectal cancer, endometrial or uterine carcinoma, salivarygland carcinoma, kidney cancer, renal cell carcinoma, liver cancer,prostate cancer, vulval cancer, thyroid cancer, hepatic carcinoma, braincancer, endometrial cancer, testis cancer, cholangiocarcinoma,gallbladder carcinoma, gastric cancer, melanoma, and various types ofhead and neck cancer (including squamous cell carcinoma of the head andneck).

The term “recurrent cancer” refers to a cancer that has returned after aprevious treatment regimen, following which there was a period of timeduring which the cancer could not be detected.

The term “progressive cancer” is a cancer that has increased in size ortumor spread since the beginning of a treatment regimen. In certainembodiments, a progressive cancer is a cancer that has increased in sizeor tumor spread by at least 10%, at least 20%, at least 30%, at least40%, or at least 50% since the beginning of a treatment regimen.

By way of example, an “anti-cancer agent” promotes cancer regression ina subject. In some embodiments, a therapeutically effective amount ofthe drug promotes cancer regression to the point of eliminating thecancer. “Promoting cancer regression” means that administering aneffective amount of the drug, alone or in combination with ananti-cancer agent, results in a reduction in tumor growth or size,necrosis of the tumor, a decrease in severity of at least one diseasesymptom, an increase in frequency and duration of disease symptom-freeperiods, or a prevention of impairment or disability due to the diseaseaffliction. In addition, the terms “effective” and “effectiveness” withregard to a treatment includes both pharmacological effectiveness andphysiological safety. Pharmacological effectiveness refers to theability of the drug to promote cancer regression in the patient.Physiological safety refers to the level of toxicity, or other adversephysiological effects at the cellular, organ and/or organism level(adverse effects) resulting from administration of the drug.

By way of example for the treatment of tumors, a therapeuticallyeffective amount of an anti-cancer agent can inhibit cell growth,inhibit tumor growth, or reduce tumor size by at least about 5%, atleast about 10%, by at least about 15%, at least about 20%, by at leastabout 25%, by at least about 30%, by at least about 40%, by at leastabout 50%, by at least about 60%, by at least about 70%, or by at leastabout 80%, by at least about 90%, by at least about 95%, or by at leastabout 100% relative to untreated subjects, relative to baseline, or, incertain embodiments, relative to patients treated with astandard-of-care therapy. In other embodiments of the invention, tumorregression can be observed and continue for a period of at least about20 days, at least about 40 days, or at least about 60 days.Notwithstanding these ultimate measurements of therapeuticeffectiveness, evaluation of immunotherapeutic drugs must also makeallowance for “immune-related” response patterns.

By way of example for the treatment of tumors, a therapeuticallyeffective amount of an anti-cancer agent can inhibit cell growth ortumor growth by at least about 20%, by at least about 30%, by at leastabout 40%, by at least about 50%, by at least about 60%, by at leastabout 70%, or by at least about 80% relative to untreated subjects.

In other embodiments of the invention, tumor regression can be observedand continue for a period of at least about 20 days, at least about 40days, or at least about 60 days. Notwithstanding these ultimatemeasurements of therapeutic effectiveness, evaluation ofimmunotherapeutic drugs must also make allowance for “immune-related”response patterns.

An “immune-related” response pattern refers to a clinical responsepattern often observed in cancer patients treated with immunotherapeuticagents that produce antitumor effects by inducing cancer-specific immuneresponses or by modifying native immune processes. This response patternis characterized by a beneficial therapeutic effect that follows aninitial increase in tumor burden or the appearance of new lesions, whichin the evaluation of traditional chemotherapeutic agents would beclassified as disease progression and would be synonymous with drugfailure. Accordingly, proper evaluation of immunotherapeutic agents canrequire long-term monitoring of the effects of these agents on thetarget disease.

A “chemotherapeutic agent” is a chemical compound useful in thetreatment of cancer. Examples of chemotherapeutic agents include, butare not limited to, alkylating agents such as thiotepa and Cytoxan®cyclosphosphamide; alkyl sulfonates such as busulfan, improsulfan andpiposulfan; aziridines such as benzodopa, carboquone, meturedopa, anduredopa; ethylenimines and methylamelamines including altretamine,triethylenemelamine, trietylenephosphoramide,triethiylenethiophosphoramide and trimethylolomelamine; acetogenins(especially bullatacin and bullatacinone); a camptothecin (including thesynthetic analogue topotecan); bryostatin; callystatin; CC-1065(including its adozelesin, carzelesin and bizelesin syntheticanalogues); cryptophycins (particularly cryptophycin 1 and cryptophycin8); dolastatin; duocarmycin (including the synthetic analogues, KW-2189and CB1-TM1); eleutherobin; pancratistatin; a sarcodictyin;spongistatin; nitrogen mustards such as chlorambucil, chlornaphazine,cholophosphamide, estramustine, ifosfamide, mechlorethamine,mechlorethamine oxide hydrochloride, melphalan, novembichin,phenesterine, prednimustine, trofosfamide, uracil mustard; nitrosureassuch as carmustine, chlorozotocin, fotemustine, lomustine, nimustine,and ranimnustine; antibiotics such as the enediyne antibiotics (e.g.,calicheamicin, especially calicheamicin gamma1I and calicheamicinomegall (see, e.g., Agnew, Chem Intl. Ed. Engl., 33: 183-186 (1994));dynemicin, including dynemicin A; bisphosphonates, such as clodronate;an esperamicin; as well as neocarzinostatin chromophore and relatedchromoprotein enediyne antiobiotic chromophores), aclacinomysins,actinomycin, authramycin, azaserine, bleomycins, cactinomycin,carabicin, carminomycin, carzinophilin, chromomycinis, dactinomycin,daunorubicin, detorubicin, 6-diazo-5-oxo-L-norleucine, Adriamycin®doxorubicin (including morpholino-doxorubicin,cyanomorpholino-doxorubicin, 2-pyrrolino-doxorubicin anddeoxydoxorubicin), epirubicin, esorubicin, idarubicin, marcellomycin,mitomycins such as mitomycin C, mycophenolic acid, nogalamycin,olivomycins, peplomycin, potfiromycin, puromycin, quelamycin,rodorubicin, streptonigrin, streptozocin, tubercidin, ubenimex,zinostatin, zorubicin; anti-metabolites such as methotrexate and5-fluorouracil (5-FU); folic acid analogues such as denopterin,methotrexate, pteropterin, trimetrexate; purine analogs such asfludarabine, 6-mercaptopurine, thiamiprine, thioguanine; pyrimidineanalogs such as ancitabine, azacitidine, 6-azauridine, carmofur,cytarabine, dideoxyuridine, doxifluridine, enocitabine, floxuridine;androgens such as calusterone, dromostanolone propionate, epitiostanol,mepitiostane, testolactone; anti-adrenals such as aminoglutethimide,mitotane, trilostane; folic acid replenisher such as frolinic acid;aceglatone; aldophosphamide glycoside; aminolevulinic acid; eniluracil;amsacrine; bestrabucil; bisantrene; edatraxate; defofamine; demecolcine;diaziquone; elfornithine; elliptinium acetate; an epothilone; etoglucid;gallium nitrate; hydroxyurea; lentinan; lonidainine; maytansinoids suchas maytansine and ansamitocins; mitoguazone; mitoxantrone; mopidanmol;nitraerine; pentostatin; phenamet; pirarubicin; losoxantrone;podophyllinic acid; 2-ethylhydrazide; procarbazine; PSK® polysaccharidecomplex (JHS Natural Products, Eugene, Oreg.); razoxane; rhizoxin;sizofiran; spirogermanium; tenuazonic acid; triaziquone;2,2′,2″-trichlorotriethylamine; trichothecenes (especially T-2 toxin,verracurin A, roridin A and anguidine); urethan; vindesine; dacarbazine;mannomustine; mitobronitol; mitolactol; pipobroman; gacytosine;arabinoside (“Ara-C”); cyclophosphamide; thiotepa; taxoids, e.g., Taxol®paclitaxel (Bristol-Myers Squibb Oncology, Princeton, N.J.), Abraxane®Cremophor-free, albumin-engineered nanoparticle formulation ofpaclitaxel (American Pharmaceutical Partners, Schaumberg, Ill.), andTaxotere® doxetaxel (Rhone-Poulenc Rorer, Antony, France); chloranbucil;Gemzar® gemcitabine; 6-thioguanine; mercaptopurine; methotrexate;platinum analogs such as cisplatin, oxaliplatin and carboplatin;vinblastine; platinum; etoposide (VP-16); ifosfamide; mitoxantrone;vincristine; Navelbine® vinorelbine; novantrone; teniposide; edatrexate;daunomycin; aminopterin; xeloda; ibandronate; irinotecan (Camptosar,CPT-11) (including the treatment regimen of irinotecan with 5-FU andleucovorin); topoisomerase inhibitor RFS 2000; difluorometlhylornithine(DMFO); retinoids such as retinoic acid; capecitabine; combretastatin;leucovorin (LV); oxaliplatin, including the oxaliplatin treatmentregimen (FOLFOX); inhibitors of PKC-alpha, Raf, H-Ras, EGFR (e.g.,erlotinib (Tarceva®)) and VEGF-A that reduce cell proliferation andpharmaceutically acceptable salts, acids or derivatives of any of theabove.

Further nonlimiting exemplary chemotherapeutic agents includeanti-hormonal agents that act to regulate or inhibit hormone action oncancers such as anti-estrogens and selective estrogen receptormodulators (SERMs), including, for example, tamoxifen (includingNolvadex® tamoxifen), raloxifene, droloxifene, 4-hydroxytamoxifen,trioxifene, keoxifene, LY117018, onapristone, and Fareston® toremifene;aromatase inhibitors that inhibit the enzyme aromatase, which regulatesestrogen production in the adrenal glands, such as, for example,4(5)-imidazoles, aminoglutethimide, Megase® megestrol acetate, Aromasin®exemestane, formestanie, fadrozole, Rivisor® vorozole, Femara®letrozole, and Arimidex® anastrozole; and anti-androgens such asflutamide, nilutamide, bicalutamide, leuprolide, and goserelin; as wellas troxacitabine (a 1,3-dioxolane nucleoside cytosine analog); antisenseoligonucleotides, particularly those which inhibit expression of genesin signaling pathways implicated in abherant cell proliferation, suchas, for example, PKC-alpha, Ralf and H-Ras; ribozymes such as a VEGFexpression inhibitor (e.g., Angiozyme® ribozyme) and a HER2 expressioninhibitor; vaccines such as gene therapy vaccines, for example,Allovectin® vaccine, Leuvectin® vaccine, and Vaxid® vaccine; Proleukin®rIL-2; Lurtotecan® topoisomerase 1 inhibitor; Abarelix® rmRH; andpharmaceutically acceptable salts, acids or derivatives of any of theabove.

An “anti-angiogenesis agent” or “angiogenesis inhibitor” refers to asmall molecular weight substance, a polynucleotide (including, e.g., aninhibitory RNA (RNAi or siRNA)), a polypeptide, an isolated protein, arecombinant protein, an antibody, or conjugates or fusion proteinsthereof, that inhibits angiogenesis, vasculogenesis, or undesirablevascular permeability, either directly or indirectly. It should beunderstood that the anti-angiogenesis agent includes those agents thatbind and block the angiogenic activity of the angiogenic factor or itsreceptor. For example, an anti-angiogenesis agent is an antibody orother antagonist to an angiogenic agent, e.g., antibodies to VEGF-A(e.g., bevacizumab (Avastin®)) or to the VEGF-A receptor (e.g., KDRreceptor or Flt-1 receptor), anti-PDGFR inhibitors such as Gleevec®(Imatinib Mesylate), small molecules that block VEGF receptor signaling(e.g., PTK787/ZK2284, SU6668, Sutent®/SU11248 (sunitinib malate),AMG706, or those described in, e.g., international patent application WO2004/113304). Anti-angiogensis agents also include native angiogenesisinhibitors, e.g., angiostatin, endostatin, etc. See, e.g., Klagsbrun andD'Amore (1991) Annu. Rev. Physiol. 53:217-39; Streit and Detmar (2003)Oncogene 22:3172-3179 (e.g., Table 3 listing anti-angiogenic therapy inmalignant melanoma); Ferrara & Alitalo (1999) Nature Medicine5(12):1359-1364; Tonini et al. (2003) Oncogene 22:6549-6556 (e.g., Table2 listing known anti-angiogenic factors); and, Sato (2003) Int. J. Clin.Oncol. 8:200-206 (e.g., Table 1 listing anti-angiogenic agents used inclinical trials).

A “growth inhibitory agent” as used herein refers to a compound orcomposition that inhibits growth of a cell (such as a cell expressingVEGF) either in vitro or in vivo. Thus, the growth inhibitory agent maybe one that significantly reduces the percentage of cells (such as acell expressing VEGF) in S phase. Examples of growth inhibitory agentsinclude, but are not limited to, agents that block cell cycleprogression (at a place other than S phase), such as agents that induceG1 arrest and M-phase arrest. Classical M-phase blockers include thevincas (vincristine and vinblastine), taxanes, and topoisomerase IIinhibitors such as doxorubicin, epirubicin, daunorubicin, etoposide, andbleomycin. Those agents that arrest G1 also spill over into S-phasearrest, for example, DNA alkylating agents such as tamoxifen,prednisone, dacarbazine, mechlorethamine, cisplatin, methotrexate,5-fluorouracil, and ara-C. Further information can be found inMendelsohn and Israel, eds., The Molecular Basis of Cancer, Chapter 1,entitled “Cell cycle regulation, oncogenes, and antineoplastic drugs” byMurakami et al. (W.B. Saunders, Philadelphia, 1995), e.g., p. 13. Thetaxanes (paclitaxel and docetaxel) are anticancer drugs both derivedfrom the yew tree. Docetaxel (Taxotere®, Rhone-Poulenc Rorer), derivedfrom the European yew, is a semisynthetic analogue of paclitaxel(Taxol®, Bristol-Myers Squibb). Paclitaxel and docetaxel promote theassembly of microtubules from tubulin dimers and stabilize microtubulesby preventing depolymerization, which results in the inhibition ofmitosis in cells.

The term “anti-neoplastic composition” refers to a composition useful intreating cancer comprising at least one active therapeutic agent.Examples of therapeutic agents include, but are not limited to, e.g.,chemotherapeutic agents, growth inhibitory agents, cytotoxic agents,agents used in radiation therapy, anti-angiogenesis agents, cancerimmunotherapeutic agents, apoptotic agents, anti-tubulin agents, andother-agents to treat cancer, such as anti-HER-2 antibodies, anti-CD20antibodies, an epidermal growth factor receptor (EGFR) antagonist (e.g.,a tyrosine kinase inhibitor), HER1/EGFR inhibitor (e.g., erlotinib(Tarceve), platelet derived growth factor inhibitors (e.g., Gleevec®(Imatinib Mesylate)), a COX-2 inhibitor (e.g., celecoxib), interferons,CTLA-4 inhibitors (e.g., anti-CTLA antibody ipilimumab (YERVOY®)), PD-1inhibitors (e.g., anti-PD-1 antibodies, BMS-936558), PD-L1 inhibitors(e.g., anti-PD-L1 antibodies, MPDL3280A), PD-L2 inhibitors (e.g.,anti-PD-L2 antibodies), TIM3 inhibitors (e.g., anti-TIM3 antibodies),cytokines, antagonists (e.g., neutralizing antibodies) that bind to oneor more of the following targets ErbB2, ErbB3, ErbB4, PDGFR-beta, BlyS,APRIL, BCMA, PD-1, PD-L1, PD-L2, CTLA-4, TIM3, or VEGF receptor(s),TRAIL/Apo2, and other bioactive and organic chemical agents, etc.Combinations thereof are also included in the invention.

An agent “antagonizes” factor activity when the agent neutralizes,blocks, inhibits, abrogates, reduces, and/or interferes with theactivity of the factor, including its binding to one or more receptorswhen the factor is a ligand.

“Treatment,” as used herein, refers to both therapeutic treatment andprophylactic or preventative measures, wherein the object is to preventor slow down (lessen) the targeted pathologic condition or disorder. Incertain embodiments, the term “treatment” covers any administration orapplication of a therapeutic for disease in a mammal, including a human,and includes inhibiting or slowing the disease or progression of thedisease; partially or fully relieving the disease, for example, bycausing regression, or restoring or repairing a lost, missing, ordefective function; stimulating an inefficient process; or causing thedisease plateau to have reduced severity. The term “treatment” alsoincludes reducing the severity of any phenotypic characteristic and/orreducing the incidence, degree, or likelihood of that characteristic.Those in need of treatment include those already with the disorder aswell as those prone to have the disorder or those in whom the disorderis to be prevented.

“Pre-treatment” or “baseline,” as used herein, refers to the status of asubject prior to administration of a particular therapy, e.g., prior toadministration of an anti-cancer agent, e.g., an immunotherapy, e.g., ananti-PD-1 Ab or an antigen binding portion thereof or an anti-CSF1R Abor an antigen binding portion thereof “Pre-treatment” can refer to thestatus of a treatment naïve subject or to a subject who has had one ormore prior therapies. Accordingly, it is possible that a subject may beconsidered to be “pre-treatment” even though the subject received someform of treatment or therapy at some time prior to the present treatmentor therapy. Furthermore, “pre-treatment” can refer to any moment upuntil the moment that a treatment is administered. For example,“pre-treatment” can include weeks, days, hours, minutes, or secondsbefore administration of the treatment. In one particular embodiment, a“pre-treatment” sample can be collected from a subject immediatelybefore administration of a first dose of the treatment or therapy.“Pre-treatment” and “baseline” are used interchangeably herein.

“On-treatment,” as used herein, refers to the status of a subject whohas received one or more initial dose of a particular therapy, e.g., ananti-cancer agent, e.g., an immunotherapy, e.g., an anti-PD-1 Ab or anantigen binding portion thereof or an anti-CSF1R Ab or an antigenbinding portion thereof “On-treatment” can refer to a subject who hasonly received a single dose or a subject who has received multiple dosesof the anti-PD-1 Ab or an antigen binding portion thereof or theanti-CSF1R Ab or an antigen binding portion thereof. In some aspects,“on-treatment” refers to a subject who is receiving an ongoing regimenof a particular therapy, e.g., the subject is being treated with ananti-PD-1 Ab or an antigen binding portion thereof or an anti-CSF1R Abor an antigen binding portion thereof. In certain embodiments, the“on-treatment” sample can be collected from a subject on about day 1, onabout day 2, on about day 3, on about day 4, on about day 5, on aboutday 6, on about day 7, on about day 8, on about day 9, on about day 10,on about day 11, on about day 12, on about day 13, on about day 14, onabout day 15, on about day 16, on about day 17, on about day 18, onabout day 19, on about day 20, on about day 21, or any combinationthereof, wherein the treatment is administered on day 1. In certainembodiments, the treatment is administration of an anti-PD-1 Ab or anantigen binding portion thereof or an anti-PD-L1 Ab or an antigenbinding portion thereof. In some embodiments, the anti-PD-1 Ab or anantigen binding portion thereof or the anti-CSF1R Ab or an antigenbinding portion thereof is administered on day 1 of every 21-day cycle.In certain embodiments, the on-treatment sample is collected from thesubject on about day 1, on about day 2, on about day 3, on about day 4,on about day 5, on about day 6, on about day 7, on about day 8, on aboutday 9, on about day 10, on about day 11, on about day 12, on about day13, on about day 14, on about day 15, on about day 16, on about day 17,on about day 18, on about day 19, on about day 20, or on about day 21 ofthe 21 day cycle, or any combination thereof. In one particularembodiment, the on-treatment sample is collected on day 1 of cycle 1,day 1 of cycle 2, day 8 of cycle 2, on day 1 of cycle 4, or anycombination thereof. In one embodiment, the on-treatment sample iscollect on day 8 of cycle 2.

Pre-treatment and on-treatment samples may be collected in the form of atumor biopsy (e.g., a core needle biopsy), partial or complete surgicalresection, blood draw, or any other method known in the art. In certainembodiments, tumor sites selected for biopsy have not received previousradiation therapy.

The term “immunotherapy” refers to the treatment of a subject afflictedwith, or at risk of contracting or suffering a recurrence of, a diseaseby a method comprising inducing, enhancing, suppressing or otherwisemodifying an immune response.

The term “effective amount” or “therapeutically effective amount” refersto an amount of a drug effective to treat a disease or disorder in asubject. In certain embodiments, an effective amount refers to an amounteffective, at dosages and for periods of time necessary, to achieve thedesired therapeutic or prophylactic result. A therapeutically effectiveamount of an anti-CSF1R antibody and/or a PD-1/PD-L1 inhibitor of theinvention may vary according to factors such as the disease state, age,sex, and weight of the individual, and the ability of the antibody orantibodies to elicit a desired response in the individual. Atherapeutically effective amount encompasses an amount in which anytoxic or detrimental effects of the antibody or antibodies areoutweighed by the therapeutically beneficial effects. In someembodiments, the expression “effective amount” refers to an amount ofthe antibody that is effective for treating the cancer. A “therapeuticamount” refers to a dosage of a drug that has been approved for use by aregulatory agency. A “subtherapeutic amount” as used herein refers to adosage of a drug or therapeutic agent that is significantly lower thanthe approved dosage. The ability of a therapeutic agent to promotedisease regression can be evaluated using a variety of methods known tothe skilled practitioner, such as in human subjects during clinicaltrials, in animal model systems predictive of efficacy in humans, or byassaying the activity of the agent in in vitro assays.

A “prophylactically effective amount” refers to an amount effective, atdosages and for periods of time necessary, to achieve the desiredprophylactic result. Typically, but not necessarily, since aprophylactic dose is used in subjects prior to or at an earlier stage ofdisease, the prophylactically effective amount would be less than thetherapeutically effective amount.

A subject may be characterized as having one or more “prior therapies”or as being “treatment naïve.” As used herein, unless otherwiseindicated, a “prior therapy” refers to any previous systemic therapy fora cancer. A “treatment naïve” subject is one that has never received anyprevious systemic therapy in the metastatic or adjuvant setting.

As used herein, the term “first dose” includes a single dose, but can bemore than one dose, i.e., multiple doses (at least two doses, at leastthree doses, or more) that are administered prior to the administrationof “a second dose” if the multiple doses are administered to determinethe susceptibility of the patient for an anti-PD-1 Ab or anti-CSF1R Abtherapy, i.e., differential expression of certain proteins (e.g.,PD-L1). The term “first dose” can also be a therapeutic dose, a dosehigher than a therapeutic dose, or a subtherapeutic dose.

The term “second dose” as used herein can also include a single dose ormultiple doses that are administered after the first dose (single doseor multiple doses). The second dose can be a therapeutic dose.

The use of the term “fixed dose” with regard to a composition or methodof the invention means that two or more different antibodies in a singlecomposition are present in the composition in particular (fixed) ratioswith each other. In some embodiments, the fixed dose is based on theweight (e.g., mg) of the antibodies. In certain embodiments, the fixeddose is based on the concentration (e.g., mg/ml) of the antibodies. Insome embodiments, the ratio is at least about 1:1, about 1:2, about 1:3,about 1:4, about 1:5, about 1:6, about 1:7, about 1:8, about 1:9, about1:10, about 1:15, about 1:20, about 1:30, about 1:40, about 1:50, about1:60, about 1:70, about 1:80, about 1:90, about 1:100, about 1:120,about 1:140, about 1:160, about 1:180, about 1:200, about 200:1, about180:1, about 160:1, about 140:1, about 120:1, about 100:1, about 90:1,about 80:1, about 70:1, about 60:1, about 50:1, about 40:1, about 30:1,about 20:1, about 15:1, about 10:1, about 9:1, about 8:1, about 7:1,about 6:1, about 5:1, about 4:1, about 3:1, or about 2:1 mg firstantibody to mg second antibody. For example, the 3:1 ratio of a firstantibody and a second antibody can mean that a vial can contain about240 mg of the first antibody and 80 mg of the second antibody or about 3mg/ml of the first antibody and 1 mg/ml of the second antibody.

The use of the term “flat dose” with regard to the composition of theinvention means a dose that is administered to a patient without regardfor the weight or body surface area (BSA) of the patient. The flat doseis, therefore, not provided as a mg/kg dose, but rather as an absoluteamount of the agent (e.g., the anti-CSF1R antibody and/or PD-1/PD-L1inhibitor). For example, a 60 kg person and a 100 kg person wouldreceive the same dose of the composition (e.g., 240 mg of an anti-PD-1antibody and 80 mg of an anti-CSF1R antibody in a single fixed dosingformulation vial containing both 240 mg of an anti-PD-1 antibody and 80mg of an anti-CSF1R antibody (or two fixed dosing formulation vialscontaining 120 mg of an anti-PD-1 antibody and 40 mg of an anti-CSF1Rantibody, etc.)).

The term “weight based dose” as referred to herein means that a dosethat is administered to a patient is calculated based on the weight ofthe patient. For example, when a patient with 60 kg body weight requires3 mg/kg of an anti-PD-1 antibody in combination with 1 mg/kg of ananti-CSF1R antibody, one can draw the appropriate amounts of theanti-PD-1 antibody (i.e., 180 mg) and the anti-CSF1R antibody (i.e., 60mg) at once from a 3:1 ratio fixed dosing formulation of an anti-PD1antibody and an anti-CSF1R antibody.

Administration “in combination with” one or more further therapeuticagents includes simultaneous (concurrent) and consecutive (sequential)administration in any order.

A “pharmaceutically acceptable carrier” refers to a non-toxic solid,semisolid, or liquid filler, diluent, encapsulating material,formulation auxiliary, or carrier conventional in the art for use with atherapeutic agent that together comprise a “pharmaceutical composition”for administration to a subject. A pharmaceutically acceptable carrieris non-toxic to recipients at the dosages and concentrations employedand is compatible with other ingredients of the formulation. Thepharmaceutically acceptable carrier is appropriate for the formulationemployed. For example, if the therapeutic agent is to be administeredorally, the carrier may be a gel capsule. If the therapeutic agent is tobe administered subcutaneously, the carrier ideally is not irritable tothe skin and does not cause injection site reaction.

The term “refractory” as applied to a treatment means a lack of partialor complete clinical response to that treatment. For example, patientsmay be considered refractory to a PD-1 or PD-L1 inhibitor if they do notshow at least a partial response after receiving at least 2 doses of theinhibitor.

Patients classified as “stage III” or “stage IIIB” or “stage IV” or“grade IV” and the like are so classified based upon the classificationsystems for their particular disease. For example, NSCLC patients may beclassified, for example, as “stage IIIB” or “stage IV” according toversion 7 of the International Association for the Study of Lung CancerStaging manual in Thoracic oncology. Melanoma patients may be classed as“stage III” or “IV” as per the American Joint Committee on Cancerstaging system. Malignant glioma patients may be classified as “gradeIV” based upon the World Health Organization standards.

Anti-CSF1R Antibodies

Anti-CSF1R antibodies include, but are not limited to, humanizedantibodies, chimeric antibodies, mouse antibodies, human antibodies, andantibodies comprising the heavy chain and/or light chain CDRs discussedherein.

Exemplary Humanized Antibodies

In some embodiments, humanized antibodies that bind CSF1R are provided.Humanized antibodies are useful as therapeutic molecules becausehumanized antibodies reduce or eliminate the human immune response tonon-human antibodies (such as the human anti-mouse antibody (HAMA)response), which can result in an immune response to an antibodytherapeutic, and decreased effectiveness of the therapeutic.

Nonlimiting exemplary humanized antibodies include huAb1 through huAb16,described herein. Nonlimiting exemplary humanized antibodies alsoinclude antibodies comprising a heavy chain variable region of anantibody selected from huAb1 to huAb16 and/or a light chain variableregion of an antibody selected from huAb1 to huAb16. Nonlimitingexemplary humanized antibodies include antibodies comprising a heavychain variable region selected from SEQ ID NOs: 39 to 45 and/or a lightchain variable region selected from SEQ ID NOs: 46 to 52. Exemplaryhumanized antibodies also include, but are not limited to, humanizedantibodies comprising heavy chain CDR1, CDR2, and CDR3, and/or lightchain CDR1, CDR2, and CDR3 of an antibody selected from 0301, 0302, and0311.

In some embodiments, a humanized anti-CSF1R antibody comprises heavychain CDR1, CDR2, and CDR3 and/or a light chain CDR1, CDR2, and CDR3 ofan antibody selected from 0301, 0302, and 0311. Nonlimiting exemplaryhumanized anti-CSF1R antibodies include antibodies comprising sets ofheavy chain CDR1, CDR2, and CDR3 selected from: SEQ ID NOs: 15, 16, and17; SEQ ID NOs: 21, 22, and 23; and SEQ ID NOs: 27, 28, and 29.Nonlimiting exemplary humanized anti-CSF1R antibodies also includeantibodies comprising sets of light chain CDR1, CDR2, and CDR3 selectedfrom: SEQ ID NOs: 18, 19, and 20; SEQ ID NOs: 24, 25, and 26; and SEQ IDNOs: 30, 31, and 32.

Nonlimiting exemplary humanized anti-CSF1R antibodies include antibodiescomprising the sets of heavy chain CDR1, CDR2, and CDR3, and light chainCDR1, CDR2, and CDR3 in Table 1 (SEQ ID NOs shown; see Table 8 forsequences). Each row of Table 1 shows the heavy chain CDR1, CDR2, andCDR3, and light chain CDR1, CDR2, and CDR3 of an exemplary antibody.

TABLE 1 Heavy chain and light chain CDRs Heavy chain Light chain CDR1CDR2 CDR3 CDR1 CDR2 CDR3 Ab SEQ ID SEQ ID SEQ ID SEQ ID SEQ ID SEQ ID0301 15 16 17 18 19 20 0302 21 22 23 24 25 26 0311 27 28 29 30 31 32

Further Exemplary Humanized Antibodies

In some embodiments, a humanized anti-CSF1R antibody comprises a heavychain comprising a variable region sequence that is at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identical to asequence selected from SEQ ID NOs: 9, 11, 13, and 39 to 45, and whereinthe antibody binds CSF1R. In some embodiments, a humanized anti-CSF1Rantibody comprises a light chain comprising a variable region sequencethat is at least 90%, at least 91%, at least 92%, at least 93%, at least94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least99% identical to a sequence selected from SEQ ID NOs: 10, 12, 14, and 46to 52, wherein the antibody binds CSF1R. In some embodiments, ahumanized anti-CSF1R antibody comprises a heavy chain comprising avariable region sequence that is at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, or at least 99% identical to a sequence selected fromSEQ ID NOs: 9, 11, 13, and 39 to 45; and a light chain comprising avariable region sequence that is at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, or at least 99% identical to a sequence selected fromSEQ ID NOs: 10, 12, 14, and 46 to 52; wherein the antibody binds CSF1R.

As used herein, whether a particular polypeptide is, for example, atleast 95% identical to an amino acid sequence can be determined using,e.g., a computer program. When determining whether a particular sequenceis, for example, 95% identical to a reference sequence, the percentageof identity is calculated over the full length of the reference aminoacid sequence.

In some embodiments, a humanized anti-CSF1R antibody comprises at leastone of the CDRs discussed herein. That is, in some embodiments, ahumanized anti-CSF1R antibody comprises at least one CDR selected from aheavy chain CDR1 discussed herein, a heavy chain CDR2 discussed herein,a heavy chain CDR3 discussed herein, a light chain CDR1 discussedherein, a light chain CDR2 discussed herein, and a light chain CDR3discussed herein. Further, in some embodiments, a humanized anti-CSF1Rantibody comprises at least one mutated CDR based on a CDR discussedherein, wherein the mutated CDR comprises 1, 2, 3, or 4 amino acidsubstitutions relative to the CDR discussed herein. In some embodiments,one or more of the amino acid substitutions are conservative amino acidsubstitutions. One skilled in the art can select one or more suitableconservative amino acid substitutions for a particular CDR sequence,wherein the suitable conservative amino acid substitutions are notpredicted to significantly alter the binding properties of the antibodycomprising the mutated CDR.

Exemplary humanized anti-CSF1R antibodies also include antibodies thatcompete for binding to CSF1R with an antibody described herein. Thus, insome embodiments, a humanized anti-CSF1R antibody is provided thatcompetes for binding to CSF1R with an antibody selected from Fabs 0301,0302, and 0311; and bivalent (i.e., having two heavy chains and twolight chains) antibody versions of those Fabs.

Exemplary Humanized Antibody Constant Regions

In some embodiments, a humanized antibody described herein comprises oneor more human constant regions. In some embodiments, the human heavychain constant region is of an isotype selected from IgA, IgG, and IgD.In some embodiments, the human light chain constant region is of anisotype selected from κ and λ. In some embodiments, a humanized antibodydescribed herein comprises a human IgG constant region. In someembodiments, a humanized antibody described herein comprises a humanIgG4 heavy chain constant region. In some such embodiments, a humanizedantibody described herein comprises an S241P mutation in the human IgG4constant region. In some embodiments, a humanized antibody describedherein comprises a human IgG4 constant region and a human κ light chain.

The choice of heavy chain constant region can determine whether or notan antibody will have effector function in vivo. Such effector function,in some embodiments, includes antibody-dependent cell-mediatedcytotoxicity (ADCC) and/or complement-dependent cytotoxicity (CDC), andcan result in killing of the cell to which the antibody is bound. Insome methods of treatment, including methods of treating some cancers,cell killing may be desirable, for example, when the antibody binds to acell that supports the maintenance or growth of the tumor. Exemplarycells that may support the maintenance or growth of a tumor include, butare not limited to, tumor cells themselves, cells that aid in therecruitment of vasculature to the tumor, and cells that provide ligands,growth factors, or counter-receptors that support or promote tumorgrowth or tumor survival. In some embodiments, when effector function isdesirable, an anti-CSF1R antibody comprising a human IgG1 heavy chain ora human IgG3 heavy chain is selected.

An antibody may be humanized by any method. Nonlimiting exemplarymethods of humanization include methods described, e.g., in U.S. Pat.Nos. 5,530,101; 5,585,089; 5,693,761; 5,693,762; 6,180,370; Jones etal., Nature 321: 522-525 (1986); Riechmann et al., Nature 332: 323-27(1988); Verhoeyen et al., Science 239: 1534-36 (1988); and U.S.Publication No. US 2009/0136500.

As noted above, a humanized antibody is an antibody in which at leastone amino acid in a framework region of a non-human variable region hasbeen replaced with the amino acid from the corresponding location in ahuman framework region. In some embodiments, at least two, at leastthree, at least four, at least five, at least six, at least seven, atleast eight, at least nine, at least 10, at least 11, at least 12, atleast 15, or at least 20 amino acids in the framework regions of anon-human variable region are replaced with an amino acid from one ormore corresponding locations in one or more human framework regions.

In some embodiments, some of the corresponding human amino acids usedfor substitution are from the framework regions of different humanimmunoglobulin genes. That is, in some such embodiments, one or more ofthe non-human amino acids may be replaced with corresponding amino acidsfrom a human framework region of a first human antibody or encoded by afirst human immunoglobulin gene, one or more of the non-human aminoacids may be replaced with corresponding amino acids from a humanframework region of a second human antibody or encoded by a second humanimmunoglobulin gene, one or more of the non-human amino acids may bereplaced with corresponding amino acids from a human framework region ofa third human antibody or encoded by a third human immunoglobulin gene,etc. Further, in some embodiments, all of the corresponding human aminoacids being used for substitution in a single framework region, forexample, FR2, need not be from the same human framework. In someembodiments, however, all of the corresponding human amino acids beingused for substitution are from the same human antibody or encoded by thesame human immunoglobulin gene.

In some embodiments, an antibody is humanized by replacing one or moreentire framework regions with corresponding human framework regions. Insome embodiments, a human framework region is selected that has thehighest level of homology to the non-human framework region beingreplaced. In some embodiments, such a humanized antibody is aCDR-grafted antibody.

In some embodiments, following CDR-grafting, one or more framework aminoacids are changed back to the corresponding amino acid in a mouseframework region. Such “back mutations” are made, in some embodiments,to retain one or more mouse framework amino acids that appear tocontribute to the structure of one or more of the CDRs and/or that maybe involved in antigen contacts and/or appear to be involved in theoverall structural integrity of the antibody. In some embodiments, tenor fewer, nine or fewer, eight or fewer, seven or fewer, six or fewer,five or fewer, four or fewer, three or fewer, two or fewer, one, or zeroback mutations are made to the framework regions of an antibodyfollowing CDR grafting.

In some embodiments, a humanized antibody also comprises a human heavychain constant region and/or a human light chain constant region.

Exemplary Chimeric Antibodies

In some embodiments, an anti-CSF1R antibody is a chimeric antibody. Insome embodiments, an anti-CSF1R antibody comprises at least onenon-human variable region and at least one human constant region. Insome such embodiments, all of the variable regions of an anti-CSF1Rantibody are non-human variable regions, and all of the constant regionsof an anti-CSF1R antibody are human constant regions. In someembodiments, one or more variable regions of a chimeric antibody aremouse variable regions. The human constant region of a chimeric antibodyneed not be of the same isotype as the non-human constant region, ifany, it replaces. Chimeric antibodies are discussed, e.g., in U.S. Pat.No. 4,816,567; and Morrison et al. Proc. Natl. Acad. Sci. USA 81:6851-55 (1984).

Nonlimiting exemplary chimeric antibodies include chimeric antibodiescomprising the heavy and/or light chain variable regions of an antibodyselected from 0301, 0302, and 0311. Additional nonlimiting exemplarychimeric antibodies include chimeric antibodies comprising heavy chainCDR1, CDR2, and CDR3, and/or light chain CDR1, CDR2, and CDR3 of anantibody selected from 0301, 0302, and 0311.

Nonlimiting exemplary chimeric anti-CSF1R antibodies include antibodiescomprising the following pairs of heavy and light chain variableregions: SEQ ID NOs: 9 and 10; SEQ ID NOs: 11 and 12; and SEQ ID NOs: 13and 14.

Nonlimiting exemplary anti-CSF1R antibodies include antibodiescomprising a set of heavy chain CDR1, CDR2, and CDR3, and light chainCDR1, CDR2, and CDR3 shown above in Table 1.

Further Exemplary Chimeric Antibodies

In some embodiments, a chimeric anti-CSF1R antibody comprises a heavychain comprising a variable region sequence that is at least 90%, atleast 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identical to asequence selected from SEQ ID NOs: 9, 11, 13, and 39 to 45, wherein theantibody binds CSF1R. In some embodiments, a chimeric anti-CSF1Rantibody comprises a light chain comprising a variable region sequencethat is at least 90%, at least 91%, at least 92%, at least 93%, at least94%, at least 95%, at least 96%, at least 97%, at least 98%, or at least99% identical to a sequence selected from SEQ ID NOs: 10, 12, 14, and 46to 52, wherein the antibody binds CSF1R. In some embodiments, a chimericanti-CSF1R antibody comprises a heavy chain comprising a variable regionsequence that is at least 90%, at least 91%, at least 92%, at least 93%,at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, orat least 99% identical to a sequence selected from SEQ ID NOs: 9, 11,13, and 39 to 45; and a light chain comprising a variable regionsequence that is at least 90%, at least 91%, at least 92%, at least 93%,at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, orat least 99% identical to a sequence selected from SEQ ID NOs: 10, 12,14, and 46 to 52; wherein the antibody binds CSF1R.

In some embodiments, a chimeric anti-CSF1R antibody comprises at leastone of the CDRs discussed herein. That is, in some embodiments, achimeric anti-CSF1R antibody comprises at least one CDR selected from aheavy chain CDR1 discussed herein, a heavy chain CDR2 discussed herein,a heavy chain CDR3 discussed herein, a light chain CDR1 discussedherein, a light chain CDR2 discussed herein, and a light chain CDR3discussed herein. Further, in some embodiments, a chimeric anti-CSF1Rantibody comprises at least one mutated CDR based on a CDR discussedherein, wherein the mutated CDR comprises 1, 2, 3, or 4 amino acidsubstitutions relative to the CDR discussed herein. In some embodiments,one or more of the amino acid substitutions are conservative amino acidsubstitutions. One skilled in the art can select one or more suitableconservative amino acid substitutions for a particular CDR sequence,wherein the suitable conservative amino acid substitutions are notpredicted to significantly alter the binding properties of the antibodycomprising the mutated CDR.

Exemplary chimeric anti-CSF1R antibodies also include chimericantibodies that compete for binding to CSF1R with an antibody describedherein. Thus, in some embodiments, a chimeric anti-CSF1R antibody isprovided that competes for binding to CSF1R with an antibody selectedfrom Fabs 0301, 0302, and 0311; and bivalent (i.e., having two heavychains and two light chains) antibody versions of those Fabs.

Exemplary Chimeric Antibody Constant Regions

In some embodiments, a chimeric antibody described herein comprises oneor more human constant regions. In some embodiments, the human heavychain constant region is of an isotype selected from IgA, IgG, and IgD.In some embodiments, the human light chain constant region is of anisotype selected from κ and λ. In some embodiments, a chimeric antibodydescribed herein comprises a human IgG constant region. In someembodiments, a chimeric antibody described herein comprises a human IgG4heavy chain constant region. In some such embodiments, a chimericantibody described herein comprises an S241P mutation in the human IgG4constant region. In some embodiments, a chimeric antibody describedherein comprises a human IgG4 constant region and a human κ light chain.

As noted above, whether or not effector function is desirable may dependon the particular method of treatment intended for an antibody. Thus, insome embodiments, when effector function is desirable, a chimericanti-CSF1R antibody comprising a human IgG1 heavy chain constant regionor a human IgG3 heavy chain constant region is selected. In someembodiments, when effector function is not desirable, a chimericanti-CSF1R antibody comprising a human IgG4 or IgG2 heavy chain constantregion is selected.

Exemplary Human Antibodies

Human antibodies can be made by any suitable method. Nonlimitingexemplary methods include making human antibodies in transgenic micethat comprise human immunoglobulin loci. See, e.g., Jakobovits et al.,Proc. Natl. Acad. Sci. USA 90: 2551-55 (1993); Jakobovits et al., Nature362: 255-8 (1993); Lonberg et al., Nature 368: 856-9 (1994); and U.S.Pat. Nos. 5,545,807; 6,713,610; 6,673,986; 6,162,963; 5,545,807;6,300,129; 6,255,458; 5,877,397; 5,874,299; and 5,545,806.

Nonlimiting exemplary methods also include making human antibodies usingphage display libraries. See, e.g., Hoogenboom et al., J. Mol. Biol.227: 381-8 (1992); Marks et al., J. Mol. Biol. 222: 581-97 (1991); andPCT Publication No. WO 99/10494.

In some embodiments, a human anti-CSF1R antibody binds to a polypeptidehaving the sequence of SEQ ID NO: 1. Exemplary human anti-CSF1Rantibodies also include antibodies that compete for binding to CSF1Rwith an antibody described herein. Thus, in some embodiments, a humananti-CSF1R antibody is provided that competes for binding to CSF1R withan antibody selected from Fabs 0301, 0302, and 0311, and bivalent (i.e.,having two heavy chains and two light chains) antibody versions of thoseFabs.

In some embodiments, a human anti-CSF1R antibody comprises one or morehuman constant regions. In some embodiments, the human heavy chainconstant region is of an isotype selected from IgA, IgG, and IgD. Insome embodiments, the human light chain constant region is of an isotypeselected from κ and λ. In some embodiments, a human antibody describedherein comprises a human IgG constant region. In some embodiments, ahuman antibody described herein comprises a human IgG4 heavy chainconstant region. In some such embodiments, a human antibody describedherein comprises an S241P mutation in the human IgG4 constant region. Insome embodiments, a human antibody described herein comprises a humanIgG4 constant region and a human κ light chain.

In some embodiments, when effector function is desirable, a humananti-CSF1R antibody comprising a human IgG1 heavy chain constant regionor a human IgG3 heavy chain constant region is selected. In someembodiments, when effector function is not desirable, a human anti-CSF1Rantibody comprising a human IgG4 or IgG2 heavy chain constant region isselected.

Additional Exemplary Anti-CSF1R Antibodies

Exemplary anti-CSF1R antibodies also include, but are not limited to,mouse, humanized, human, chimeric, and engineered antibodies thatcomprise, for example, one or more of the CDR sequences describedherein. In some embodiments, an anti-CSF1R antibody comprises a heavychain variable region described herein. In some embodiments, ananti-CSF1R antibody comprises a light chain variable region describedherein. In some embodiments, an anti-CSF1R antibody comprises a heavychain variable region described herein and a light chain variable regiondescribed herein. In some embodiments, an anti-CSF1R antibody comprisesheavy chain CDR1, CDR2, and CDR3 described herein. In some embodiments,an anti-CSF1R antibody comprises light chain CDR1, CDR2, and CDR3described herein. In some embodiments, an anti-CSF1R antibody comprisesheavy chain CDR1, CDR2, and CDR3 described herein and light chain CDR1,CDR2, and CDR3 described herein.

In some embodiments, an anti-CSF1R antibody comprises a heavy chainvariable region of an antibody selected from Fabs 0301, 0302, and 0311.Nonlimiting exemplary anti-CSF1R antibodies also include antibodiescomprising a heavy chain variable region of an antibody selected fromhumanized antibodies huAb1 to huAb16. Nonlimiting exemplary anti-CSF1Rantibodies include antibodies comprising a heavy chain variable regioncomprising a sequence selected from SEQ ID NOs: 9, 11, 13, and 39 to 45.

In some embodiments, an anti-CSF1R antibody comprises a light chainvariable region of an antibody selected from Fabs 0301, 0302, and 0311.Nonlimiting exemplary anti-CSF1R antibodies also include antibodiescomprising a light chain variable region of an antibody selected fromhumanized antibodies huAb1 to huAb16. Nonlimiting exemplary anti-CSF1Rantibodies include antibodies comprising a light chain variable regioncomprising a sequence selected from SEQ ID NOs: 10, 12, 14, and 46 to52.

In some embodiments, an anti-CSF1R antibody comprises a heavy chainvariable region and a light chain variable region of an antibodyselected from Fabs 0301, 0302, and 0311. Nonlimiting exemplaryanti-CSF1R antibodies also include antibodies comprising a heavy chainvariable region and a light chain variable region of an antibodyselected from humanized antibodies huAb1 to huAb16. Nonlimitingexemplary anti-CSF1R antibodies include antibodies comprising thefollowing pairs of heavy and light chain variable regions: SEQ ID NOs: 9and 10; SEQ ID NOs: 11 and 12; and SEQ ID NOs: 13 and 14; SEQ ID NOs: 39and 40; SEQ ID NOs: 41 and 42; SEQ ID NOs: 43 and 44; SEQ ID NOs: 45 and46; SEQ ID NOs: 47 and 48; SEQ ID NOs: 49 and 50; and SEQ ID NOs: 51 and52. Nonlimiting exemplary anti-CSF1R antibodies also include antibodiescomprising the following pairs of heavy and light chains: SEQ ID NOs: 33and 34; SEQ ID NOs: 35 and 36; and SEQ ID NOs: 37 and 38.

In some embodiments, an anti-CSF1R antibody comprises heavy chain CDR1,CDR2, and CDR3 of an antibody selected from Fabs 0301, 0302, and 0311.Nonlimiting exemplary anti-CSF1R antibodies include antibodiescomprising sets of heavy chain CDR1, CDR2, and CDR3 selected from: SEQID NOs: 15, 16, and 17; SEQ ID NOs: 21, 22, and 23; and SEQ ID NOs: 27,28, and 29.

In some embodiments, an anti-CSF1R antibody comprises light chain CDR1,CDR2, and CDR3 of an antibody selected from Fabs 0301, 0302, and 0311.Nonlimiting exemplary anti-CSF1R antibodies include antibodiescomprising sets of light chain CDR1, CDR2, and CDR3 selected from: SEQID NOs: 18, 19, and 20; SEQ ID NOs: 24, 25, and 26; and SEQ ID NOs: 30,31, and 32.

In some embodiments, an anti-CSF1R antibody comprises heavy chain CDR1,CDR2, and CDR3, and light chain CDR1, CDR2, and CDR3 of an antibodyselected from Fabs 0301, 0302, and 0311.

Nonlimiting exemplary anti-CSF1R antibodies include antibodiescomprising the sets of heavy chain CDR1, CDR2, and CDR3, and light chainCDR1, CDR2, and CDR3 shown above in Table 1.

Further Exemplary Antibodies

In some embodiments, an anti-CSF1R antibody comprises a heavy chaincomprising a variable region sequence that is at least 90%, at least91%, at least 92%, at least 93%, at least 94%, at least 95%, at least96%, at least 97%, at least 98%, or at least 99% identical to a sequenceselected from SEQ ID NOs: 9, 11, 13, and 39 to 45, wherein the antibodybinds CSF1R. In some embodiments, an anti-CSF1R antibody comprises alight chain comprising a variable region sequence that is at least 90%,at least 91%, at least 92%, at least 93%, at least 94%, at least 95%, atleast 96%, at least 97%, at least 98%, or at least 99% identical to asequence selected from SEQ ID NOs: 10, 12, 14, and 46 to 52, wherein theantibody binds CSF1R. In some embodiments, an anti-CSF1R antibodycomprises a heavy chain comprising a variable region sequence that is atleast 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99%identical to a sequence selected from SEQ ID NOs: 9, 11, 13, and 39 to45; and a light chain comprising a variable region sequence that is atleast 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99%identical to a sequence selected from SEQ ID NOs: 10, 12, 14, and 46 to52; wherein the antibody binds CSF1R.

In some embodiments, an anti-CSF1R antibody comprises at least one ofthe CDRs discussed herein. That is, in some embodiments, an anti-CSF1Rantibody comprises at least one CDR selected from a heavy chain CDR1discussed herein, a heavy chain CDR2 discussed herein, a heavy chainCDR3 discussed herein, a light chain CDR1 discussed herein, a lightchain CDR2 discussed herein, and a light chain CDR3 discussed herein.Further, in some embodiments, an anti-CSF1R antibody comprises at leastone mutated CDR based on a CDR discussed herein, wherein the mutated CDRcomprises 1, 2, 3, or 4 amino acid substitutions relative to the CDRdiscussed herein. In some embodiments, one or more of the amino acidsubstitutions are conservative amino acid substitutions. One skilled inthe art can select one or more suitable conservative amino acidsubstitutions for a particular CDR sequence, wherein the suitableconservative amino acid substitutions are not predicted to significantlyalter the binding properties of the antibody comprising the mutated CDR.

Exemplary anti-CSF1R antibodies also include antibodies that compete forbinding to CSF1R with an antibody described herein. Thus, in someembodiments, an anti-CSF1R antibody is provided that competes forbinding to CSF1R with an antibody selected from Fabs 0301, 0302, and0311, and bivalent (i.e., having two heavy chains and two light chains)antibody versions of those Fabs.

Exemplary Antibody Constant Regions

In some embodiments, an antibody described herein comprises one or morehuman constant regions. In some embodiments, the human heavy chainconstant region is of an isotype selected from IgA, IgG, and IgD. Insome embodiments, the human light chain constant region is of an isotypeselected from κ and λ. In some embodiments, an antibody described hereincomprises a human IgG constant region. In some embodiments, an antibodydescribed herein comprises a human IgG4 heavy chain constant region. Insome such embodiments, an antibody described herein comprises an S241Pmutation in the human IgG4 constant region. In some embodiments, anantibody described herein comprises a human IgG4 constant region and ahuman κ light chain.

As noted above, whether or not effector function is desirable may dependon the particular method of treatment intended for an antibody. Thus, insome embodiments, when effector function is desirable, an anti-CSF1Rantibody comprising a human IgG1 heavy chain constant region or a humanIgG3 heavy chain constant region is selected. In some embodiments, wheneffector function is not desirable, an anti-CSF1R antibody comprising ahuman IgG4 or IgG2 heavy chain constant region is selected.

Exemplary Anti-CSF1R Heavy Chain Variable Regions

In some embodiments, anti-CSF1R antibody heavy chain variable regionsare provided. In some embodiments, an anti-CSF1R antibody heavy chainvariable region is a mouse variable region, a human variable region, ora humanized variable region.

An anti-CSF1R antibody heavy chain variable region comprises a heavychain CDR1, FR2, CDR2, FR3, and CDR3. In some embodiments, an anti-CSF1Rantibody heavy chain variable region further comprises a heavy chain FR1and/or FR4. Nonlimiting exemplary heavy chain variable regions include,but are not limited to, heavy chain variable regions having an aminoacid sequence selected from SEQ ID NOs: 9, 11, 13, and 39 to 45.

In some embodiments, an anti-CSF1R antibody heavy chain variable regioncomprises a CDR1 comprising a sequence selected from SEQ ID NOs: 15, 21,and 27.

In some embodiments, an anti-CSF1R antibody heavy chain variable regioncomprises a CDR2 comprising a sequence selected from SEQ ID NOs: 16, 22,and 28.

In some embodiments, an anti-CSF1R antibody heavy chain variable regioncomprises a CDR3 comprising a sequence selected from SEQ ID NOs: 17, 23,and 29.

Nonlimiting exemplary heavy chain variable regions include, but are notlimited to, heavy chain variable regions comprising sets of CDR1, CDR2,and CDR3 selected from: SEQ ID NOs: 15, 16, and 17; SEQ ID NOs: 21, 22,and 23; and SEQ ID NOs: 27, 28, and 29.

In some embodiments, an anti-CSF1R antibody heavy chain comprises avariable region sequence that is at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, or at least 99% identical to a sequence selected fromSEQ ID NOs: 9, 11, 13, and 39 to 45, wherein the heavy chain, togetherwith a light chain, is capable of forming an antibody that binds CSF1R.

In some embodiments, an anti-CSF1R antibody heavy chain comprises atleast one of the CDRs discussed herein. That is, in some embodiments, ananti-CSF1R antibody heavy chain comprises at least one CDR selected froma heavy chain CDR1 discussed herein, a heavy chain CDR2 discussedherein, and a heavy chain CDR3 discussed herein. Further, in someembodiments, an anti-CSF1R antibody heavy chain comprises at least onemutated CDR based on a CDR discussed herein, wherein the mutated CDRcomprises 1, 2, 3, or 4 amino acid substitutions relative to the CDRdiscussed herein. In some embodiments, one or more of the amino acidsubstitutions are conservative amino acid substitutions. One skilled inthe art can select one or more suitable conservative amino acidsubstitutions for a particular CDR sequence, wherein the suitableconservative amino acid substitutions are not predicted to significantlyalter the binding properties of the heavy chain comprising the mutatedCDR.

In some embodiments, a heavy chain comprises a heavy chain constantregion. In some embodiments, a heavy chain comprises a human heavy chainconstant region. In some embodiments, the human heavy chain constantregion is of an isotype selected from IgA, IgG, and IgD. In someembodiments, the human heavy chain constant region is an IgG constantregion. In some embodiments, a heavy chain comprises a human igG4 heavychain constant region. In some such embodiments, the human IgG4 heavychain constant region comprises an S241P mutation.

In some embodiments, when effector function is desirable, a heavy chaincomprises a human IgG1 or IgG3 heavy chain constant region. In someembodiments, when effector function is less desirable, a heavy chaincomprises a human IgG4 or IgG2 heavy chain constant region.

Exemplary Anti-CSF1R Light Chain Variable Regions

In some embodiments, anti-CSF1R antibody light chain variable regionsare provided. In some embodiments, an anti-CSF1R antibody light chainvariable region is a mouse variable region, a human variable region, ora humanized variable region.

An anti-CSF1R antibody light chain variable region comprises a lightchain CDR1, FR2, CDR2, FR3, and CDR3. In some embodiments, an anti-CSF1Rantibody light chain variable region further comprises a light chain FR1and/or FR4. Nonlimiting exemplary light chain variable regions includelight chain variable regions having an amino acid sequence selected fromSEQ ID NOs: 10, 12, 14, and 46 to 52.

In some embodiments, an anti-CSF1R antibody light chain variable regioncomprises a CDR1 comprising a sequence selected from SEQ ID NOs: 18, 24and 30.

In some embodiments, an anti-CSF1R antibody light chain variable regioncomprises a CDR2 comprising a sequence selected from SEQ ID NOs: 19, 25,and 31.

In some embodiments, an anti-CSF1R antibody light chain variable regioncomprises a CDR3 comprising a sequence selected from SEQ ID NOs: 20, 26,and 32.

Nonlimiting exemplary light chain variable regions include, but are notlimited to, light chain variable regions comprising sets of CDR1, CDR2,and CDR3 selected from: SEQ ID NOs: 18, 19, and 20; SEQ ID NOs: 24, 25,and 26; and SEQ ID NOs: 30, 31, and 32.

In some embodiments, an anti-CSF1R antibody light chain comprises avariable region sequence that is at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least97%, at least 98%, or at least 99% identical to a sequence selected fromSEQ ID NOs: 10, 12, 14, and 46 to 52, wherein the light chain, togetherwith a heavy chain, is capable of forming an antibody that binds CSF1R.

In some embodiments, an anti-CSF1R antibody light chain comprises atleast one of the CDRs discussed herein. That is, in some embodiments, ananti-CSF1R antibody light chain comprises at least one CDR selected froma light chain CDR1 discussed herein, a light chain CDR2 discussedherein, and a light chain CDR3 discussed herein. Further, in someembodiments, an anti-CSF1R antibody light chain comprises at least onemutated CDR based on a CDR discussed herein, wherein the mutated CDRcomprises 1, 2, 3, or 4 amino acid substitutions relative to the CDRdiscussed herein. In some embodiments, one or more of the amino acidsubstitutions are conservative amino acid substitutions. One skilled inthe art can select one or more suitable conservative amino acidsubstitutions for a particular CDR sequence, wherein the suitableconservative amino acid substitutions are not predicted to significantlyalter the binding properties of the light chain comprising the mutatedCDR.

In some embodiments, a light chain comprises a human light chainconstant region. In some embodiments, a human light chain constantregion is selected from a human κ and a human λ light chain constantregion.

Exemplary Additional CSF1R Binding Molecules

In some embodiments, additional molecules that bind CSF1R are provided.Such molecules include, but are not limited to, non-canonical scaffolds,such as anti-calins, adnectins, ankyrin repeats, etc. See, e.g., Hosseet al., Prot. Sci. 15:14 (2006); Fiedler, M. and Skerra, A.,“Non-Antibody Scaffolds,” pp. 467-499 in Handbook of TherapeuticAntibodies, Dubel, S., ed., Wiley-VCH, Weinheim, Germany, 2007.

Exemplary Properties of Anti-CSF1R Antibodies

In some embodiments, an antibody having a structure described abovebinds to the CSF1R with a binding affinity (K_(D)) of less than 1 nM,blocks binding of CSF1 and/or IL-34 to CSF1R, and inhibits CSF1Rphosphorylation induced by CSF1 and/or IL-34.

In some embodiments, an anti-CSF1R antibody binds to the extracellulardomain of CSF1R (CSF1R-ECD). In some embodiments, an anti-CSF1R antibodyhas a binding affinity (K_(D)) for CSF1R of less than 1 nM, less than0.5 nM, less than 0.1 nM, or less than 0.05 nM. In some embodiments, ananti-CSF1R antibody has a K_(D) of between 0.01 and 1 nM, between 0.01and 0.5 nM, between 0.01 and 0.1 nM, between 0.01 and 0.05 nM, orbetween 0.02 and 0.05 nM.

In some embodiments, an anti-CSF1R antibody blocks ligand binding toCSF1R. In some embodiments, an anti-CSF1R antibody blocks binding ofCSF1 to CSF1R. In some embodiments, an anti-CSF1R antibody blocksbinding of IL-34 to CSF1R. In some embodiments, an anti-CSF1R antibodyblocks binding of both CSF1 and IL-34 to CSF1R. In some embodiments, anantibody that blocks ligand binding binds to the extracellular domain ofCSF1R. In some embodiments, an antibody blocks ligand binding to CSF1Rwhen it reduces the amount of detectable binding of a ligand to CSF1R byat least 50%, using the assay described, e.g., U.S. Pat. No. 8,206,715B2, Example 7, which is incorporated herein by reference for anypurpose. In some embodiments, an antibody reduces the amount ofdetectable binding of a ligand to CSF1R by at least 60%, at least 70%,at least 80%, or at least 90%. In some such embodiments, the antibody issaid to block ligand binding by at least 50%, at least 60%, at least70%, etc.

In some embodiments, an anti-CSF1R antibody inhibits ligand-inducedCSF1R phosphorylation. In some embodiments, an anti-CSF1R antibodyinhibits CSF1-induced CSF1R phosphorylation. In some embodiments, ananti-CSF1R antibody inhibits IL-34-induced CSF1R phosphorylation. Insome embodiments, an anti-CSF1R antibody inhibits both CSF1-induced andIL-34-induced CSF1R phosphorylation. In some embodiments, an antibody isconsidered to “inhibit ligand-induced CSF1R phosphorylation” when itreduces the amount of detectable ligand-induced CSF1R phosphorylation byat least 50%, using the assay described, e.g., U.S. Pat. No. 8,206,715B2, Example 6, which is incorporated herein by reference for anypurpose. In some embodiments, an antibody reduces the amount ofdetectable ligand-induced CSF1R phosphorylation by at least 60%, atleast 70%, at least 80%, or at least 90%. In some such embodiments, theantibody is said to inhibit ligand-induced CSF1R phosphorylation by atleast at least 50%, at least 60%, at least 70%, etc.

In some embodiments, an antibody inhibits monocyte proliferation and/orsurvival responses in the presence of CSF1 and/or IL-34. In someembodiments, an antibody is considered to “inhibit monocyteproliferation and/or survival responses” when it reduces the amount ofmonocyte proliferation and/or survival responses in the presence of CSF1and/or IL-34 by at least 50%, using the assay described, e.g., U.S. Pat.No. 8,206,715 B2, Example 10, which is incorporated herein by referencefor any purpose. In some embodiments, an antibody reduces the amount ofmonocyte proliferation and/or survival responses in the presence of CSF1and/or IL-34 by at least 60%, at least 70%, at least 80%, or at least90%. In some such embodiments, the antibody is said to inhibit monocyteproliferation and/or survival responses by at least at least 50%, atleast 60%, at least 70%, etc.

Exemplary PD-1/PD-L1 Inhibitors

Exemplary PD-1/PD-L1 inhibitors include antibodies that inhibit PD-1,such as anti-PD-1 antibodies and anti-PD-L1 antibodies. Such antibodiesmay be humanized antibodies, chimeric antibodies, mouse antibodies,human antibodies, and antibodies comprising the heavy chain and/or lightchain CDRs discussed herein. PD-1/PD-L1 inhibitors also include fusionproteins that block binding of PD-1 to PD-L1, such as AMP-22. Variousanti-PD-1 antibodies are known in the art.

Anti-PD-1 Antibodies

PD-1 is a key immune checkpoint receptor expressed by activated T and Bcells and mediates immunosuppression. PD-1 is a member of the CD28family of receptors, which includes CD28, CTLA-4, ICOS, PD-1, and BTLA.Two cell surface glycoprotein ligands for PD-1 have been identified,Programmed Death Ligand-1 (PD-L1) and Programmed Death Ligand-2 (PD-L2),that are expressed on antigen-presenting cells as well as many humancancers and have been shown to down regulate T cell activation andcytokine secretion upon binding to PD-1. Inhibition of the PD-1/PD-L1interaction mediates potent antitumor activity in preclinical models.

HuMAbs that bind specifically to PD-1 with high affinity have beendisclosed in U.S. Pat. No. 8,008,449. Other anti-PD-1 mAbs have beendescribed in, for example, U.S. Pat. Nos. 6,808,710, 7,488,802,8,168,757 and 8,354,509, and PCT Publication No. WO 2012/145493. Each ofthe anti-PD-1 HuMAbs disclosed in U.S. Pat. No. 8,008,449 has beendemonstrated to exhibit one or more of the following characteristics:(a) binds to human PD-1 with a K_(D) of 1×10⁻⁷ M or less, as determinedby surface plasmon resonance using a Biacore biosensor system; (b) doesnot substantially bind to human CD28, CTLA-4 or ICOS; (c) increasesT-cell proliferation in a Mixed Lymphocyte Reaction (MLR) assay; (d)increases interferon-γ production in an MLR assay; (e) increases IL-2secretion in an MLR assay; (0 binds to human PD-1 and cynomolgus monkeyPD-1; (g) inhibits the binding of PD-L1 and/or PD-L2 to PD-1; (h)stimulates antigen-specific memory responses; (i) stimulates Abresponses; and/or (j) inhibits tumor cell growth in vivo. Anti-PD-1 Absusable in the present invention include mAbs that bind specifically tohuman PD-1 and exhibit at least one, at least two, at least three, atleast four or at least five of the preceding characteristics.

Exemplary anti-PD-1 antibodies also include, but are not limited to,mouse, humanized, human, chimeric, and engineered antibodies thatcomprise, for example, one or more of the CDR sequences describedherein. In some embodiments, an anti-PD-1 antibody comprises a heavychain variable region described herein. In some embodiments, ananti-PD-1 antibody comprises a light chain variable region describedherein. In some embodiments, an anti-PD-1 antibody comprises a heavychain variable region described herein and a light chain variable regiondescribed herein. In some embodiments, an anti-PD-1 antibody comprisesheavy chain CDR1, CDR2, and CDR3 described herein, e.g., comprising SEQID NOs: 105, 107, and 109. In some embodiments, an anti-PD-1 antibodycomprises light chain CDR1, CDR2, and CDR3 described herein, e.g.,comprising SEQ ID NOs: 112, 114, and 116. In some embodiments, ananti-PD-1 antibody comprises heavy chain CDR1, CDR2, and CDR3 describedherein, e.g., comprising SEQ ID NOs: 105, 107, and 109, and light chainCDR1, CDR2, and CDR3 described herein, e.g., comprising SEQ ID NOs: 112,114, and 116.

In some embodiments, an anti-PD-1 antibody comprises heavy chain CDR1,CDR2, and CDR3 comprising SEQ ID NOs: 105, 107, and 109 respectively. Insome embodiments, an anti-PD-1 antibody comprises light chain CDR1,CDR2, and CDR3 comprising SEQ ID NOs: 112, 114, and 116, respectively.In some embodiments, the anti-PD-1 antibody comprises a heavy chainvariable region comprising SEQ ID NO: 100. In some embodiments, theanti-PD-1 antibody comprises a light chain variable region comprisingSEQ ID NO: 102. In some embodiments, the anti-PD-1 antibody comprises aheavy chain variable region comprising SEQ ID NO: 100 and a light chainvariable region comprising SEQ ID NO: 102. In some embodiments, theanti-PD-1 antibody comprises a heavy chain constant region comprisingSEQ ID NO: 101 and/or a light chain constant region comprising SEQ IDNO: 103.

Further Exemplary Antibodies

In some embodiments, an anti-PD-1 antibody comprises a heavy chaincomprising a variable region sequence that is at least 90%, at least91%, at least 92%, at least 93%, at least 94%, at least 95%, at least96%, at least 97%, at least 98%, or at least 99% identical to SEQ IDNOs:100, wherein the antibody binds PD-1. In some embodiments, ananti-PD-1 antibody comprises a light chain comprising a variable regionsequence that is at least 90%, at least 91%, at least 92%, at least 93%,at least 94%, at least 95%, at least 96%, at least 97%, at least 98%, orat least 99% identical to SEQ ID NOs:102, wherein the antibody bindsPD-1. In some embodiments, an anti-PD-1 antibody comprises a heavy chaincomprising a variable region sequence that is at least 90%, at least91%, at least 92%, at least 93%, at least 94%, at least 95%, at least96%, at least 97%, at least 98%, or at least 99% identical to SEQ IDNOs:100; and a light chain comprising a variable region sequence that isat least 90%, at least 91%, at least 92%, at least 93%, at least 94%, atleast 95%, at least 96%, at least 97%, at least 98%, or at least 99%identical to SEQ ID NOs:102; wherein the antibody binds PD-1.

In some embodiments, an anti-PD-1 antibody comprises at least one of theCDRs discussed herein. That is, in some embodiments, an anti-PD-1antibody comprises at least one CDR selected from a heavy chain CDR1discussed herein, a heavy chain CDR2 discussed herein, a heavy chainCDR3 discussed herein, a light chain CDR1 discussed herein, a lightchain CDR2 discussed herein, and a light chain CDR3 discussed herein.Further, in some embodiments, an anti-PD-1 antibody comprises at leastone mutated CDR based on a CDR discussed herein, wherein the mutated CDRcomprises 1, 2, 3, or 4 amino acid substitutions relative to the CDRdiscussed herein. In some embodiments, one or more of the amino acidsubstitutions are conservative amino acid substitutions. One skilled inthe art can select one or more suitable conservative amino acidsubstitutions for a particular CDR sequence, wherein the suitableconservative amino acid substitutions are not predicted to significantlyalter the binding properties of the antibody comprising the mutated CDR.

In one embodiment, the anti-PD-1 Ab is nivolumab. Nivolumab (also knownas “Opdivo®”; formerly designated 5C4, BMS-936558, MDX-1106, orONO-4538) is a fully human IgG4 (S228P) PD-1 immune checkpoint inhibitorAb that selectively prevents interaction with PD-1 ligands (PD-L1 andPD-L2), thereby blocking the down-regulation of antitumor T-cellfunctions (U.S. Pat. No. 8,008,449; Wang et al., 2014 Cancer ImmunolRes. 2(9):846-56).

In another embodiment, the anti-PD-1 Ab is pembrolizumab. Pembrolizumab(also known as “Keytrude”, lambrolizumab, and MK-3475) is a humanizedmonoclonal IgG4 antibody directed against human cell surface receptorPD-1 (programmed death-1 or programmed cell death-1). Pembrolizumab isdescribed, for example, in U.S. Pat. No. 8,900,587; see alsohttp://www.cancer.gov/drugdictionary?cdrid=695789 (last accessed: Dec.14, 2014). Pembrolizumab has been approved by the FDA for the treatmentof relapsed or refractory melanoma.

In other embodiments, the anti-PD-1 Ab is MEDI0608 (formerly AMP-514),which is a monoclonal antibody against the PD-1 receptor. MEDI0608 isdescribed, for example, in U.S. Pat. No. 8,609,089,B2 or inhttp://www.cancer.gov/drugdictionary?cdrid=756047 (last accessed Dec.14, 2014).

Anti-PD-1 Abs usable in the disclosed methods also include isolated Absthat bind specifically to human PD-1 and cross-compete for binding tohuman PD-1 with nivolumab (see, e.g., U.S. Pat. No. 8,008,449; WO2013/173223). The ability of Abs to cross-compete for binding to anantigen indicates that these Abs bind to the same epitope region of theantigen and sterically hinder the binding of other cross-competing Absto that particular epitope region. These cross-competing Abs areexpected to have functional properties very similar to those ofnivolumab by virtue of their binding to the same epitope region of PD-1.Cross-competing Abs can be readily identified based on their ability tocross-compete with nivolumab in standard PD-1 binding assays such asBiacore analysis, ELISA assays or flow cytometry (see, e.g., WO2013/173223).

In certain embodiments, the Abs that cross-compete for binding to humanPD-1 with, or bind to the same epitope region of human PD-1 as,nivolumab are mAbs. For administration to human subjects, thesecross-competing Abs can be chimeric Abs, or can be humanized or humanAbs. Such chimeric, humanized or human mAbs can be prepared and isolatedby methods well known in the art.

Anti-PD-1 Abs usable in the methods of the disclosed invention alsoinclude antigen-binding portions of the above Abs. It has been amplydemonstrated that the antigen-binding function of an Ab can be performedby fragments of a full-length Ab. Examples of binding fragmentsencompassed within the term “antigen-binding portion” of an Ab include(i) a Fab fragment, a monovalent fragment consisting of the V_(L),V_(H), C_(L) and C_(H1) domains; (ii) a F(ab′)2 fragment, a bivalentfragment comprising two Fab fragments linked by a disulfide bridge atthe hinge region; (iii) a Fd fragment consisting of the V_(H) and C_(H1)domains; and (iv) a Fv fragment consisting of the V_(L) and V_(H)domains of a single arm of an Ab.

A nonlimiting exemplary fusion protein that is a PD-1/PD-L1 inhibitor isAMP-224 (Amplimmune, GlaxoSmithKline).

A nonlimiting exemplay peptide that is a PD-1/PD-L1 inhibitor isAUR-012.

Exemplary Antibody Conjugates

In some embodiments, an antibody is conjugated to a label and/or acytotoxic agent. As used herein, a label is a moiety that facilitatesdetection of the antibody and/or facilitates detection of a molecule towhich the antibody binds. Nonlimiting exemplary labels include, but arenot limited to, radioisotopes, fluorescent groups, enzymatic groups,chemiluminescent groups, biotin, epitope tags, metal-binding tags, etc.One skilled in the art can select a suitable label according to theintended application.

As used herein, a cytotoxic agent is a moiety that reduces theproliferative capacity of one or more cells. A cell has reducedproliferative capacity when the cell becomes less able to proliferate,for example, because the cell undergoes apoptosis or otherwise dies, thecell fails to proceed through the cell cycle and/or fails to divide, thecell differentiates, etc. Nonlimiting exemplary cytotoxic agentsinclude, but are not limited to, radioisotopes, toxins, andchemotherapeutic agents. One skilled in the art can select a suitablecytotoxic according to the intended application.

In some embodiments, a label and/or a cytotoxic agent is conjugated toan antibody using chemical methods in vitro. Nonlimiting exemplarychemical methods of conjugation are known in the art, and includeservices, methods and/or reagents commercially available from, e.g.,Thermo Scientific Life Science Research Produces (formerly Pierce;Rockford, Ill.), Prozyme (Hayward, Calif.), SACRI Antibody Services(Calgary, Canada), AbD Serotec (Raleigh, N.C.), etc. In someembodiments, when a label and/or cytotoxic agent is a polypeptide, thelabel and/or cytotoxic agent can be expressed from the same expressionvector with at least one antibody chain to produce a polypeptidecomprising the label and/or cytotoxic agent fused to an antibody chain.One skilled in the art can select a suitable method for conjugating alabel and/or cytotoxic agent to an antibody according to the intendedapplication.

Exemplary Leader Sequences

In order for some secreted proteins to express and secrete in largequantities, a leader sequence from a heterologous protein may bedesirable. In some embodiments, a leader sequence is selected from SEQID NOs: 3 and 4, which are light chain and heavy chain leader sequences,respectively. In some embodiments, employing heterologous leadersequences may be advantageous in that a resulting mature polypeptide mayremain unaltered as the leader sequence is removed in the ER during thesecretion process. The addition of a heterologous leader sequence may berequired to express and secrete some proteins.

Certain exemplary leader sequence sequences are described, e.g., in theonline Leader sequence Database maintained by the Department ofBiochemistry, National University of Singapore. See Choo et al., BMCBioinformatics, 6: 249 (2005); and PCT Publication No. WO 2006/081430.

Nucleic Acid Molecules Encoding Antibodies

Nucleic acid molecules comprising polynucleotides that encode one ormore chains of an antibody are provided. In some embodiments, a nucleicacid molecule comprises a polynucleotide that encodes a heavy chain or alight chain of an antibody. In some embodiments, a nucleic acid moleculecomprises both a polynucleotide that encodes a heavy chain and apolynucleotide that encodes a light chain, of an antibody. In someembodiments, a first nucleic acid molecule comprises a firstpolynucleotide that encodes a heavy chain and a second nucleic acidmolecule comprises a second polynucleotide that encodes a light chain.

In some such embodiments, the heavy chain and the light chain areexpressed from one nucleic acid molecule, or from two separate nucleicacid molecules, as two separate polypeptides. In some embodiments, suchas when an antibody is an scFv, a single polynucleotide encodes a singlepolypeptide comprising both a heavy chain and a light chain linkedtogether.

In some embodiments, a polynucleotide encoding a heavy chain or lightchain of an antibody comprises a nucleotide sequence that encodes aleader sequence, which, when translated, is located at the N terminus ofthe heavy chain or light chain. As discussed above, the leader sequencemay be the native heavy or light chain leader sequence, or may beanother heterologous leader sequence.

Nucleic acid molecules may be constructed using recombinant DNAtechniques conventional in the art. In some embodiments, a nucleic acidmolecule is an expression vector that is suitable for expression in aselected host cell.

Antibody Expression and Production

Vectors

Vectors comprising polynucleotides that encode antibody heavy chainsand/or light chains are provided. Vectors comprising polynucleotidesthat encode antibody heavy chains and/or light chains are also provided.Such vectors include, but are not limited to, DNA vectors, phagevectors, viral vectors, retroviral vectors, etc. In some embodiments, avector comprises a first polynucleotide sequence encoding a heavy chainand a second polynucleotide sequence encoding a light chain. In someembodiments, the heavy chain and light chain are expressed from thevector as two separate polypeptides. In some embodiments, the heavychain and light chain are expressed as part of a single polypeptide,such as, for example, when the antibody is an scFv.

In some embodiments, a first vector comprises a polynucleotide thatencodes a heavy chain and a second vector comprises a polynucleotidethat encodes a light chain. In some embodiments, the first vector andsecond vector are transfected into host cells in similar amounts (suchas similar molar amounts or similar mass amounts). In some embodiments,a mole- or mass-ratio of between 5:1 and 1:5 of the first vector and thesecond vector is transfected into host cells. In some embodiments, amass ratio of between 1:1 and 1:5 for the vector encoding the heavychain and the vector encoding the light chain is used. In someembodiments, a mass ratio of 1:2 for the vector encoding the heavy chainand the vector encoding the light chain is used.

In some embodiments, a vector is selected that is optimized forexpression of polypeptides in CHO or CHO-derived cells, or in NSO cells.Exemplary such vectors are described, e.g., in Running Deer et al.,Biotechnol. Prog. 20:880-889 (2004).

In some embodiments, a vector is chosen for in vivo expression ofantibody heavy chains and/or antibody light chains in animals, includinghumans. In some such embodiments, expression of the polypeptide is underthe control of a promoter that functions in a tissue-specific manner.For example, liver-specific promoters are described, e.g., in PCTPublication No. WO 2006/076288.

Host Cells

In various embodiments, antibody heavy chains and/or light chains may beexpressed in prokaryotic cells, such as bacterial cells; or ineukaryotic cells, such as fungal cells (such as yeast), plant cells,insect cells, and mammalian cells. Such expression may be carried out,for example, according to procedures known in the art. Exemplaryeukaryotic cells that may be used to express polypeptides include, butare not limited to, COS cells, including COS 7 cells; 293 cells,including 293-6E cells; CHO cells, including CHO—S and DG44 cells;PER.C6® cells (Crucell); and NSO cells. In some embodiments, antibodyheavy chains and/or light chains may be expressed in yeast. See, e.g.,U.S. Publication No. US 2006/0270045 A1. In some embodiments, aparticular eukaryotic host cell is selected based on its ability to makedesired post-translational modifications to the antibody heavy chainsand/or light chains. For example, in some embodiments, CHO cells producepolypeptides that have a higher level of sialylation than the samepolypeptide produced in 293 cells.

Introduction of one or more nucleic acids into a desired host cell maybe accomplished by any method, including but not limited to, calciumphosphate transfection, DEAE-dextran mediated transfection, cationiclipid-mediated transfection, electroporation, transduction, infection,etc. Nonlimiting exemplary methods are described, e.g., in Sambrook etal., Molecular Cloning, A Laboratory Manual, 3^(rd) ed. Cold SpringHarbor Laboratory Press (2001). Nucleic acids may be transiently orstably transfected in the desired host cells, according to any suitablemethod.

In some embodiments, one or more polypeptides may be produced in vivo inan animal that has been engineered or transfected with one or morenucleic acid molecules encoding the polypeptides, according to anysuitable method.

Purification of Antibodies

Antibodies may be purified by any suitable method. Such methods include,but are not limited to, the use of affinity matrices or hydrophobicinteraction chromatography. Suitable affinity ligands include theantigen and ligands that bind antibody constant regions. For example, aProtein A, Protein G, Protein A/G, or an antibody affinity column may beused to bind the constant region and to purify an antibody. Hydrophobicinteractive chromatography, for example, a butyl or phenyl column, mayalso suitable for purifying some polypeptides. Many methods of purifyingpolypeptides are known in the art.

Cell-Free Production of Antibodies

In some embodiments, an antibody is produced in a cell-free system.Nonlimiting exemplary cell-free systems are described, e.g., inSitaraman et al., Methods Mol. Biol. 498: 229-44 (2009); Spirin, TrendsBiotechnol. 22: 538-45 (2004); Endo et al., Biotechnol. Adv. 21: 695-713(2003).

Therapeutic Compositions and Methods

Methods of Treating Cancer

In some embodiments, methods for treating cancer are provided,comprising administering an effective amount of an anti-CSF1R antibodyand an effective amount of a PD-1/PD-L1 inhibitor. In some embodiments,the anti-CSF1R antibody and the PD-1/PD-L1 inhibitor are administeredconcurrently. In some embodiments, the anti-CSF1R antibody and thePD-1/PD-L1 inhibitor are administered sequentially. In some embodiments,at least one, at least two, at least three doses, at least five doses,or at least ten doses of an anti-CSF1R antibody is administered prior toadministration of a PD-1/PD-L1 inhibitor. In some embodiments, at leastone, at least two, at least three doses, at least five doses, or atleast ten doses of a PD-1/PD-L1 inhibitor is administered prior toadministration of an anti-CSF1R antibody. In some embodiments, the lastdose of PD-1/PD-L1 inhibitor is administered at least one, two, three,five, days or ten, or one, two, three, five, twelve, or twenty fourweeks prior to the first dose of CSFR1 inhibitor. In some otherembodiment, the last dose of CSFR1 inhibitor is administered at leastone, two, three, five, days or ten, or one, two, three, five, twelve, ortwenty four weeks prior to the first dose of PD-1/PD-L1 inhibitor. Insome embodiments, a subject has received, or is receiving, PD-1/PD-L1inhibitor therapy, and an anti-CSF1R antibody is added to thetherapeutic regimen.

In some embodiments, a method of selecting a patient for combinationtherapy with an anti-CSF1R antibody and a PD-1/PD-L1 inhibitor isprovided, comprising determining the levels of TAMs and/or CD8+ T cellsin the patient. In some embodiments, if a patient's TAM levels are high,the patient is selected for combination therapy. In some embodiments, ifa patient's TAM and CD8+ T cell levels are high, the patient is selectedfor combination therapy. The level of TAMs or CD8+ T cells is considered“high” if it is at least 10%, at least 20%, at least 30%, at least 40%,at least 50%, at least 75%, or at least 100% higher than the level in anindividual who does not have cancer. In some embodiments, the level ofTAMs or CD8+ T cells is considered “high” if it is above the medianlevel found in individuals with cancer. In some embodiments, if apatient's TAM levels are high and CD8+ T cell levels are low, thepatient is selected for combination therapy with an anti-CSF1R antibodyand a PD-1/PD-L1 inhibitor. The level of CD8+ T cells is considered“low” if it is at or below the median level found in individuals withcancer. In some embodiment, the level of CD8+ T cells is considered“low” if it is at least 10%, at least 20%, at least 30%, at least 40%,at least 50%, at least 75%, or at least 100% lower than the level in anindividual who does not have cancer. In some embodiments, expression ofCSF1R on the patient's TAMs is determined. In some embodiments, if thepatient's TAMs express CSF1R, the patient is selected for combinationtherapy. In some embodiments, if the patient's TAMs express elevatedlevels of CSF1R, the patient is selected for combination therapy. Insome embodiments, a patient's TAMs are considered to express “elevated”levels of CSF1R if the level of CSF1R is at or above the median level ofCSF1R found expressed on TAMS in individuals with cancer. In someembodiments, if the patient's CSF1R expression shows a high correlationwith the level of CD8+ T cells, T cells or PD-1/PD-L1 expression, thepatient is selected for combination therapy. The correlation of theexpressions is considered “high” if it is at or above the median levelfound in individuals with cancer.

Levels of TAMs, CSF1R expression, CD8+ T cells, regulatory T cells,and/or PD-1 expression may be measured by methods in the art.Nonexemplary methods include immunohistochemistry (IHC),fluorescence-activated cell sorting (FACS), protein arrays, and geneexpression assays, such as RNA sequencing, gene arrays, and quantitativePCR. In some embodiments, one or more markers selected from CSF1R, CD68,CD163, CD8, FoxP3, PD-1, and PD-L1 may be detected by IHC, FACS, or geneexpression assay on tumor sections, or dissociated cells from tumorsections.

In some embodiments, the cancer is selected from squamous cell cancer,small-cell lung cancer, pituitary cancer, esophageal cancer,astrocytoma, soft tissue sarcoma, non-small cell lung cancer,adenocarcinoma of the lung, squamous carcinoma of the lung, cancer ofthe peritoneum, hepatocellular cancer, gastrointestinal cancer,pancreatic cancer, glioblastoma, cervical cancer, ovarian cancer, livercancer, bladder cancer, hepatoma, breast cancer, colon cancer,colorectal cancer, endometrial or uterine carcinoma, salivary glandcarcinoma, kidney cancer, renal cancer, liver cancer, prostate cancer,vulval cancer, thyroid cancer, hepatic carcinoma, brain cancer,endometrial cancer, testis cancer, cholangiocarcinoma, gallbladdercarcinoma, gastric cancer, melanoma, and various types of head and neckcancer. In some embodiments, lung cancer is non-small cell lung canceror lung squamous cell carcinoma. In some embodiments, leukemia is acutemyeloid leukemia or chronic lymphocytic leukemia. In some embodiments,breast cancer is breast invasive carcinoma. In some embodiments, ovariancancer is ovarian serous cystadenocarcinoma. In some embodiments, kidneycancer is kidney renal clear cell carcinoma. In some embodiments, coloncancer is colon adenocarcinoma. In some embodiments, bladder cancer isbladder urothelial carcinoma. In some embodiments, the cancer isselected from bladder cancer, cervical cancer (such as squamous cellcervical cancer), head and neck squamous cell carcinoma, rectaladenocarcinoma, non-small cell lung cancer, endometrial cancer, prostateadenocarcinoma, colon cancer, ovarian cancer (such as serous epithelialovarian cancer), and melanoma.

In some embodiments, the anti-CSF1R antibody locks binding of CSF1and/or IL-34 to CSF1R and/or inhibits CSF1R phosphorylation induced byCSF1 and/or IL-34. In some embodiments, the anti-CSF1R antibody locksbinding of CSF1 and IL-34 to CSF1R and/or inhibits CSF1R phosphorylationinduced by CSF1 and/or IL-34. In some embodiments, the anti-CSF1Rantibody comprises the CDRs of, or the variable regions of, an antibodyselected from huAb1 to huAb16, described herein. In some embodiments,the anti-CSF1R antibody comprises the CDRs of, or the variable regionsof, huAb1.

In some embodiments, the PD-1/PD-L1 inhibitor is selected from a fusionprotein (such as AMP-224) and an antibody. In some embodiments, thePD-1/PD-L1 inhibitor is selected from an anti-PD-1 antibody and ananti-PD-L1 antibody. Nonlimiting exemplary anti-PD-1 antibodies includeantibodies comprising the CDRs of, or the variable regions of, anantibody selected from nivolumab and pembrolizumab. In some embodiments,the anti-PD-1 antibody is selected from nivolumab and pembrolizumab.Nonlimiting exemplary anti-PD-L1 antibodies include antibodiescomprising the CDRs of, or the variable regions of, an antibody selectedfrom BMS-936559, MPDL3280A, MEDI4736, and MSB0010718C. In someembodiments, the anti-PD-L1 antibody is selected from BMS-936559,MPDL3280A, MEDI4736, and MSB0010718C.

In some embodiments of the methods described herein, the subject is aPD-1/PD-L1 inhibitor inadequate responder. A subject who is a PD-1/PD-L1inhibitor inadequate responder, may have previously responded to aPD-1/PD-L1 inhibitor, but may have become less responsive to thePD-1/PD-L1 inhibitor, or the subject may have never responded to thePD-1/PD-L1 inhibitor. Inadequate response to a PD-1/PD-L1 inhibitormeans that aspects of the condition that would be expected to improvefollowing a standard dose of the PD-1/PD-L1 inhibitor do not improve,and/or improvement only occurs if greater than a standard dose isadministered. In some embodiments, a PD-1/PD-L1 inhibitor inadequateresponder has experienced, or is experiencing, an inadequate response tothe PD-1/PD-L1 inhibitor after receiving a standard dose for at leasttwo weeks, at least three weeks, at least four weeks, at least sixweeks, or at least twelve weeks. A “standard” dose is determined by amedical professional, and may depend on the subject's age, weight,healthy history, severity of disease, the frequency of dosing, etc. Insome embodiments, a PD-1/PD-L1 inhibitor inadequate responder hasexperienced, or is experiencing, an inadequate response to an anti-PD-1antibody and/or an anti-PD-L1 antibody. In some embodiments, aPD-1/PD-L1 inhibitor inadequate responder has experienced, or isexperiencing, an inadequate response to AMP-224. In some embodiments, aPD-1/PD-L1 inhibitor inadequate responder has experienced, or isexperiencing, an inadequate response to a PD-1/PD-L1 inhibitor selectedfrom nivolumab and pembrolizumab.

Routes of Administration and Carriers

In various embodiments, antibodies may be administered in vivo byvarious routes, including, but not limited to, oral, intra-arterial,parenteral, intranasal, intravenous, intramuscular, intracardiac,intraventricular, intratracheal, buccal, rectal, intraperitoneal,intradermal, topical, transdermal, and intrathecal, or otherwise byimplantation or inhalation. The subject compositions may be formulatedinto preparations in solid, semi-solid, liquid, or gaseous forms;including, but not limited to, tablets, capsules, powders, granules,ointments, solutions, suppositories, enemas, injections, inhalants, andaerosols. A nucleic acid molecule encoding an antibody may be coatedonto gold microparticles and delivered intradermally by a particlebombardment device, or “gene gun,” as described in the literature (see,e.g., Tang et al., Nature 356:152-154 (1992)). The appropriateformulation and route of administration may be selected according to theintended application.

In various embodiments, compositions comprising antibodies are providedin formulations with a wide variety of pharmaceutically acceptablecarriers (see, e.g., Gennaro, Remington: The Science and Practice ofPharmacy with Facts and Comparisons: Drugfacts Plus, 20^(th) ed. (2003);Ansel et al., Pharmaceutical Dosage Forms and Drug Delivery Systems,7^(th) ed., Lippencott Williams and Wilkins (2004); Kibbe et al.,Handbook of Pharmaceutical Excipients, 3^(rd) ed., Pharmaceutical Press(2000)). Various pharmaceutically acceptable carriers, which includevehicles, adjuvants, and diluents, are available. Moreover, variouspharmaceutically acceptable auxiliary substances, such as Ph adjustingand buffering agents, tonicity adjusting agents, stabilizers, wettingagents and the like, are also available. Non-limiting exemplary carriersinclude saline, buffered saline, dextrose, water, glycerol, ethanol, andcombinations thereof.

In various embodiments, compositions comprising antibodies may beformulated for injection, including subcutaneous administration, bydissolving, suspending, or emulsifying them in an aqueous or nonaqueoussolvent, such as vegetable or other oils, synthetic aliphatic acidglycerides, esters of higher aliphatic acids, or propylene glycol; andif desired, with conventional additives such as solubilizers, isotonicagents, suspending agents, emulsifying agents, stabilizers andpreservatives. In various embodiments, the compositions may beformulated for inhalation, for example, using pressurized acceptablepropellants such as dichlorodifluoromethane, propane, nitrogen, and thelike. The compositions may also be formulated, in various embodiments,into sustained release microcapsules, such as with biodegradable ornon-biodegradable polymers. A non-limiting exemplary biodegradableformulation includes poly lactic acid-glycolic acid polymer. Anon-limiting exemplary non-biodegradable formulation includes apolyglycerin fatty acid ester. Certain methods of making suchformulations are described, for example, in EP 1 125 584 A1.

Pharmaceutical packs and kits comprising one or more containers, eachcontaining one or more doses of an antibody or combination of antibodiesare also provided. In some embodiments, a unit dosage is providedwherein the unit dosage contains a predetermined amount of a compositioncomprising an antibody or combination of antibodies, with or without oneor more additional agents. In some embodiments, such a unit dosage issupplied in single-use prefilled syringe for injection, for example, oras a kit. In various embodiments, the composition contained in the unitdosage may comprise saline, sucrose, or the like; a buffer, such asphosphate, or the like; and/or be formulated within a stable andeffective Ph range. Alternatively, in some embodiments, the compositionmay be provided as a lyophilized powder that may be reconstituted uponaddition of an appropriate liquid, for example, sterile water. In someembodiments, the composition comprises one or more substances thatinhibit protein aggregation, including, but not limited to, sucrose andarginine. In some embodiments, a composition of the invention comprisesheparin and/or a proteoglycan.

Pharmaceutical compositions are administered in an amount effective fortreatment or prophylaxis of the specific indication. The therapeuticallyeffective amount is typically dependent on the weight of the subjectbeing treated, his or her physical or health condition, theextensiveness of the condition to be treated, or the age of the subjectbeing treated. In general, antibodies may be administered in an amountin the range of about 10 μg/kg body weight to about 100 mg/kg bodyweight per dose. In some embodiments, antibodies may be administered inan amount in the range of about 50 μg/kg body weight to about 5 mg/kgbody weight per dose. In some embodiments, antibodies may beadministered in an amount in the range of about 100 μg/kg body weight toabout 10 mg/kg body weight per dose. In some embodiments, antibodies maybe administered in an amount in the range of about 100 μg/kg body weightto about 20 mg/kg body weight per dose. In some embodiments, antibodiesmay be administered in an amount in the range of about 0.5 mg/kg bodyweight to about 20 mg/kg body weight per dose. In some embodiments, aPD-1/PD-L1 inhibitor, such as an antibody or fusion protein, isadministered at a dose of 1 to 4 mg/kg, and an anti-CSF1R antibody isadministered at a dose of 0.5 to 10 mg/kg. In some embodiments, aPD-1/PD-L1 inhibitor is administered at a dose of 1, 2, or 4 mg/kg, andan anti-CSF1R antibody is administered at a dose of about 0.3 to about10 mg/kg, about 0.5 to about 10 mg/kg, about 0.5 to about 5 mg/kg, orabout 1 to about 5 mg/kg body weight, such as at about 0.3, about 0.5,about 1, about 2, about 3, about 4, about 5, or about 10 mg/kg.

In certain embodiments, the dose of a PD-1/PD-L1 inhibitor or anti-CSF1Rantibody is a fixed dose in a pharmaceutical composition. In otherembodiments, the method of the present invention can be used with a flatdose (a dose given to a patient irrespective of the body weight of thepatient). For example, a flat dose of a nivolumab can be about 240 mg.For example, a flat dose of pembrolizumab can be about 200 mg.

In some embodiments, an anti-CSF1R Ab, when combined with the PD-1/PD-L1inhibitor, can be dosed within the range of about 0.3 to about 10 mg/kg,about 0.5 to about 10 mg/kg, about 0.5 to about 5 mg/kg, or about 1 toabout 5 mg/kg body weight, such as at about 0.3, about 0.5, about 1,about 2, about 3, about 4, about 5, or about 10 mg/kg, administeredabout every two or three weeks. In other embodiments, an anti-CSF1Rantibody is administered on a different dosage schedule from thePD-1/PD-L1 inhibitor. In some embodiments, an anti-CSF1R antibody isadministered about every week, about every two weeks, about every threeweeks, about every 4 weeks, about every five weeks, about every sixweeks, about every seven weeks, about every eight weeks, about everynine weeks, about every ten weeks, about every eleven weeks, about everytwelve weeks or about every fifteen weeks. A dosage of an anti-CSF1Rantibody or PD-1/PD-L1 inhibitor that is significantly lower than theapproved therapeutic dose may be regarded as subtherapeutic. For examplea dose of, for instance, about 0.3 mg/kg or less about every 3 or 4weeks, may be regarded as a subtherapeutic dosage in relation to atherapeutic dosage of about 3.0 mg/kg every 3 weeks. In certainembodiments, the PD-1/PD-L1 inhibitor is administered at a dosage ofabout 0.1, about 0.3, about 0.5, about 1, about 2, about 3, about 4, orabout 5 mg/kg in combination with an anti-CSF1R antibody administered ata dosage of about 0.1, about 0.3, about 0.5, about 1, about 2, about 3,about 4, about 5, or about 10 mg/kg, once about every 2 weeks, onceabout every 3 weeks, or once about every 4 weeks.

In certain embodiments, the combination of an PD-1/PD-L1 inhibitor andan anti-CSF1R Ab is administered intravenously to the subject in aninduction phase about every 2 or 3 weeks for 1, 2, 3 or 4administrations. In certain embodiments, the combination of nivolumaband anti-CSF1R Ab is administered intravenously in the induction phaseabout every 3 weeks for about 4 administrations. The induction phase isfollowed by a maintenance phase during which only the PD-1/PD-L1inhibitor is administered to the subject at a dosage of about 0.1, about0.3, about 0.5, about 1, about 2, about 3, about 4, about 5 or about 10mg/kg every two or three weeks for as long as the treatment provesefficacious or until unmanageable toxicity or disease progressionoccurs. In certain embodiments, nivolumab is administered during themaintenance phase at a dose of about 3 mg/kg body about every 2 weeks.

In certain embodiments, the PD-1/PD-L1 inhibitor and the anti-CSF1Rantibody are formulated as a single composition, wherein the dose of thePD-1/PD-L1 inhibitor and the dose of the anti-CSF1R antibody arecombined at a ratio of, for example, 1:50, 1:40, 1:30, 1:20, 1:10. 1:5,1:3, 1:1, 3:1, 5:1, 10:1, 20:1, 30:1, 40:1, or 50:1. In otherembodiments, the dose of the anti-CSF1R antibody is a fixed dose. Incertain embodiments, the dose of the anti-CSF1R antibody or PD-1/PD-L1inhibitor is a flat dose, which is given to a patient irrespective ofthe body weight. In a specific embodiment, the flat dose of thePD-1/PD-L1 inhibitor is about 80 mg.

For combination with other anti-cancer agents, these agents areadministered at their approved dosages. Treatment is continued as longas clinical benefit is observed or until unacceptable toxicity ordisease progression occurs. Nevertheless, in certain embodiments, thedosages of these anti-cancer agents administered are significantly lowerthan the approved dosage, i.e., a subtherapeutic dosage, of the agent isadministered in combination with the anti-CSF1R antibody and thePD-1/PD-L1 inhibitor. The anti-CSF1R antibody and the PD-1/PD-L1inhibitor can be administered at the dosage that has been shown toproduce the highest efficacy as monotherapy in clinical trials, e.g.,for nivolumab, about 3 mg/kg of nivolumab administered once about everythree weeks (Topalian et al., 2012a; Topalian et al., 2012), or at asignificantly lower dose, i.e., at a subtherapeutic dose.

Dosage and frequency vary depending on the half-life of the Ab in thesubject. In general, human Abs show the longest half-life, followed byhumanized Abs, chimeric Abs, and nonhuman Abs. The dosage and frequencyof administration can vary depending on whether the treatment isprophylactic or therapeutic. In prophylactic applications, a relativelylow dosage is typically administered at relatively infrequent intervalsover a long period of time. Some patients continue to receive treatmentfor the rest of their lives. In therapeutic applications, a relativelyhigh dosage at relatively short intervals is sometimes required untilprogression of the disease is reduced or terminated, or until thepatient shows partial or complete amelioration of symptoms of disease.Thereafter, the patient can be administered a prophylactic regime.

Actual dosage levels of the active ingredients in the pharmaceuticalcompositions of the present invention can be varied so as to obtain anamount of the active ingredient which is effective to achieve thedesired therapeutic response for a particular patient, composition, andmode of administration, without being unduly toxic to the patient. Theselected dosage level will depend upon a variety of pharmacokineticfactors including the activity of the particular compositions of thepresent invention employed, the route of administration, the time ofadministration, the rate of excretion of the particular compound beingemployed, the duration of the treatment, other drugs, compounds and/ormaterials used in combination with the particular compositions employed,the age, sex, weight, condition, general health and prior medicalhistory of the patient being treated, and like factors well known in themedical arts. A composition of the present invention can be administeredvia one or more routes of administration using one or more of a varietyof methods well known in the art. As will be appreciated by the skilledartisan, the route and/or mode of administration will vary dependingupon the desired results. The antibody compositions may be administeredas needed to subjects. Determination of the frequency of administrationmay be made by persons skilled in the art, such as an attendingphysician based on considerations of the condition being treated, age ofthe subject being treated, severity of the condition being treated,general state of health of the subject being treated and the like. Insome embodiments, an effective dose of an antibody is administered to asubject one or more times. In various embodiments, an effective dose ofan antibody is administered to the subject once a month, less than oncea month, such as, for example, every two months or every three months.In other embodiments, an effective dose of an antibody is administeredmore than once a month, such as, for example, every three weeks, everytwo weeks or every week. In some embodiments, an effective dose of anantibody is administered once per 1, 2, 3, 4, or 5 weeks. In someembodiments, an effective dose of an antibody is administered twice orthree times per week. An effective dose of an antibody is administeredto the subject at least once. In some embodiments, the effective dose ofan antibody may be administered multiple times, including for periods ofat least a month, at least six months, or at least a year.

Combination Therapy

Antibodies may be administered alone or with other modes of treatment.They may be provided before, substantially contemporaneous with, orafter other modes of treatment, for example, surgery, chemotherapy,radiation therapy, or the administration of a biologic, such as anothertherapeutic antibody. In some embodiments, the cancer has recurred orprogressed following a therapy selected from surgery, chemotherapy, andradiation therapy, or a combination thereof.

For treatment of cancer, as discussed herein, the antibodies may beadministered in conjunction with one or more additional anti-canceragents, such as the chemotherapeutic agent, growth inhibitory agent,anti-angiogenesis agent and/or anti-neoplastic composition. Nonlimitingexamples of chemotherapeutic agent, growth inhibitory agent,anti-angiogenesis agent, anti-cancer agent and anti-neoplasticcomposition that can be used in combination with the antibodies of thepresent invention are provided herein under “Definitions.”

EXAMPLES

The examples discussed below are intended to be purely exemplary of theinvention and should not be considered to limit the invention in anyway. The examples are not intended to represent that the experimentsbelow are all or the only experiments performed. Efforts have been madeto ensure accuracy with respect to numbers used (for example, amounts,temperature, etc.) but some experimental errors and deviations should beaccounted for. Unless indicated otherwise, parts are parts by weight,molecular weight is weight average molecular weight, temperature is indegrees Centigrade, and pressure is at or near atmospheric.

Example 1: Humanized Anti-CSF1R Antibodies

Various humanized anti-CSF1R antibodies were developed previously. See,e.g., PCT Publication No. WO 2011/140249.

The sequences for each of the humanized heavy chain variable regions andhumanized light chain variable regions, aligned with the sequences ofthe parental chimeric antibody variable regions and the sequences of thehuman acceptor variable framework regions are shown in FIGS. 1 (heavychains) and 2 (light chains). The changes in humanized variable regionsequences relative to the human acceptor variable framework regionsequences are boxed. Each of the CDRs for each of the variable regionsis shown in a boxed region, and labeled as “CDR” above the boxedsequences.

Table 8, below, shows the full sequences for the humanized heavy chainsand humanized light chains of antibodies huAb1 to huAb16. The name andSEQ ID Nos of the humanized heavy chain and humanized light chain ofeach of those antibodies is shown in Table 3.

TABLE 3 Humanized heavy chains and light chains of huAb1 to huAb16Humanized Humanized Humanized antibody HC SEQ ID NO LC SEQ ID NO huAb1h0301-H0 53 h0301-L0 60 huAb2 h0301-H1 54 h0301-L0 60 huAb3 h0301-H2 55h0301-L0 60 huAb4 h0301-H0 53 h0301-L1 61 huAb5 h0301-H1 54 h0301-L1 61huAb6 h0301-H2 55 h0301-L1 61 huAb7 h0302-H1 56 h0302-L0 62 huAb8h0302-H1 56 h0302-L1 63 huAb9 h0302-H1 56 h0302-L2 64 huAb10 h0302-H2 57h0302-L0 62 huAb11 h0302-H2 57 h0302-L1 63 huAb12 h0302-H2 57 h0302-L264 huAb13 h0311-H1 58 h0311-L0 65 huAb14 h0311-H1 58 h0311-L1 66 huAb15h0311-H2 59 h0311-L0 65 huAb16 h0311-H2 59 h0311-L1 66

The 16 humanized antibodies were tested for binding to human, cynomolgusmonkey, and mouse CSF1R ECD, as described previously. See, e.g., PCTPublication No. WO 2011/140249. The antibodies were found to bind toboth human and cynomolgus monkey CSF1R ECD, but not to mouse CSF1R ECD.The humanized antibodies were also found to block binding of CSF1 andIL-34 to both human and cynomolgus CSF1R and to inhibit CSF1-induced andIL-34-induced phosphorylation of human CSF1R expressed in CHO cells.See, e.g., PCT Publication No. WO 2011/140249.

The k_(a), k_(d), and K_(D) for binding to human CSF1R ECD werepreviously determined and are shown in Table 4. See, e.g., PCTPublication No. WO 2011/140249.

TABLE 4 Humanized antibody binding affinity for human CSF1R huAb k_(a)(M⁻¹s⁻¹) K_(d) (s⁻¹) K_(D) (Nm) huAb 0301-L0H0 3.22 × 10⁶ 1.11 × 10⁻⁰³0.35 huAb 0301-L0H1 3.56 × 10⁶ 1.22 × 10⁻⁰³ 0.34 huAb 0301-L0H2 2.32 ×10⁶ 6.60 × 10⁻⁰⁴ 0.28 huAb 0301-L1H0 3.29 × 10⁶ 1.15 × 10⁻⁰³ 0.35 huAb0301-L1H1 2.87 × 10⁶ 9.21 × 10⁻⁰⁴ 0.32 huAb 0301-L1H2 2.95 × 10⁶ 7.42 ×10⁻⁰⁴ 0.25 huAb 0302-L0H1 3.54 × 10⁶ 3.69 × 10⁻⁰³ 1.04 huAb 0302-L1H13.47 × 10⁶ 4.04 × 10⁻⁰³ 1.17 huAb 0302-L2H1 1.60 × 10⁶ 9.14 × 10⁻⁰⁴ 0.57huAb 0302-L0H2 3.40 × 10⁶ 1.79 × 10⁻⁰³ 0.53 huAb 0302-L1H2 2.71 × 10⁶1.53 × 10⁻⁰³ 0.56 huAb 0302-L2H2 1.84 × 10⁶ 8.40 × 10⁻⁰⁴ 0.46 huAb0311-L0H1 1.22 × 10⁶ 5.40 × 10⁻⁰⁴ 0.44 huAb 0311-L1H1 1.32 × 10⁶ 6.64 ×10⁻⁰⁴ 0.50 huAb 0311-L0H2 1.34 × 10⁶ 4.73 × 10⁻⁰⁴ 0.35 huAb 0311-L1H21.51 × 10⁶ 6.09 × 10⁻⁰⁴ 0.40

Example 2: Correlation of CSF1R Expression and T Cell Signature inTumors

To determine the correlation between cancer T cell signatures and CSF1Rexpression, mRNA expression data from the The Cancer Genome Atlas wasused. The Cancer Genome Atlas is a publicly accessible databaseresulting from a joint effort of the National Cancer Institute (NCI) andthe National Human Genome Research Institute (NHGRI). Seecancergenome.nih.gov. mRNA levels are determined using the IlluminaRNASeq platform. FOXP3, CTLA-4, CD274, PDCD1, CD8A and GZMB correlationsare calculated for all genes in the RNASeq data and for each cancertype. The correlations are then ranked. There are approximately 20486genes in the RNASeq data, so for each gene, a correlation rank isassigned to every other gene. As an example, for FOXP3 in colon cancer,the correlation ranks range from 1 to 20486. CSF1R has a correlationrank of 38, suggesting that it highly correlated to FOXP3 expression.The high correlation of FOXP3 and CSF1R is consistent with thehypothesis that a subset of colon cancers have tumor associatedmacrophages (TAMs) expressing CSF1R and FOXP3-expressing Treg cells.Extending this analysis to many cancer types and the gene markers can beused to produce a heat map showing the cancer tissues that have CSF1Rexpression correlated with Treg cells, CD8+ T-cells, and PD-L1expression. See FIG. 3.

Example 3: Effect of Anti-CSF1R Antibody and an Anti-PD-1 Antibody onMouse Colorectal Tumors In Vivo

Seven week old female C57BL/6 mice were purchased from HarlanLaboratories (Livermore, Calif.) and were acclimated for six days beforethe start of the study. The murine colorectal carcinoma cell line MC38was implanted subcutaneously over the right flank of the mice at 0.5×10⁶cells/100 μl/mouse. Prior to inoculation, the cells were cultured forthree passages in RPMI 1640 medium supplemented with 10%heat-inactivated Fetal Bovine Serum (FBS), 2 mM L-Glutamine. Cells weregrown at 37° C. in a humidified atmosphere with 5% CO₂. Upon reaching80-85% confluence, cells were harvested and resuspended in coldserum-free RPMI 1640 at 5×10⁶ cells per milliliter.

Mice were monitored twice weekly following cell implantation for tumorgrowth. For tumor measurements, the length and width of each tumor wasmeasured using calipers and volume was calculated according to theformula: Tumor volume (mm³)=(width (mm)×length (mm))²/2. On Day 7, alltumors were measured, and mice were randomly assigned to treatmentgroups. The mean tumor volume for all animals enrolled into treatmentgroups was 58 mm³. Dosing groups were as follows: 1) Mouse IgG1 (Bio XCell, West Lebanon, N.H., USA; Clone MOPC-21) plus Rat IgG2a (Bio XCell, Clone 2A3), 2) anti-CSF1R (Bio X Cell, Clone AFS98) plus RatIgG2a, 3) anti-PD-1 (Bio X Cell, Clone RMP1-14) plus Mouse IgG1, or 4)anti-CSF1R plus anti-PD-1. Tumors continued to be measured at leasttwice per week until tumor volume exceeded 10% of animal weight, orapproximately 2000 mm³.

The change in tumor size is shown by graphing mean tumor volume relativeto the day upon which animals were inoculated with MC38 cells. Treatmentwith either anti-CSF1R or anti-PD-1 significantly reduced tumor growthcompared to IgG control (P<0.05). The combination of anti-CSF1R andanti-PD-1 resulted in significantly reduced tumor growth compared toeither anti-CSF1R or anti-PD-1 alone (P<0.05). P-values were calculatedusing unpaired, two-tailed t-test analyses of the calculated tumorvolumes on day 11 after initiation of treatment. (See FIGS. 4A and 4B.)

Example 4: Effect of Anti-CSF1R Antibody and an Anti-PD-1 Antibody onMouse Pancreatic Tumors In Vivo

Eight week old female FVB mice were purchased from Jackson Laboratoriesand were acclimated for two weeks before the start of the study. Amurine pancreatic adenocarcinoma cell line derived fromKras^(G12D)/Ink4a^(−/−) transgenic mice was surgically implanted intothe pancreas of the mice at 0.2×10⁶ cells/50 μl/mouse. Prior toinoculation, the cells were cultured for no more than three passages inDMEM medium supplemented with 10% heat-inactivated Fetal Bovine Serum(FBS). Cells were grown at 37° C. in a humidified atmosphere with 5%CO₂. Upon reaching 80-85% confluence, cells were harvested andresuspended in cold PBS with Matrigel at 4×10⁶ cells per milliliter.

Mice were monitored twice weekly following cell implantation for tumorgrowth. Mice were gently palpated at least twice per week to assess therelative size of the pancreatic tumors. On Day 12, all tumors wereassessed, and mice were randomly assigned to treatment groups. Dosinggroups were as follows: 1) Mouse IgG1 (Bio X Cell; Clone MOPC-21) plusvehicle control, 2) anti-CSF1R antibody (murine antibody with similaraffinity for murine CSF1R as that of huAB1 for human CSF1R) plusvehicle, 3) anti-CSF1R plus gemcitabine (GEM), 4) anti-PD-1 antibody(Bio X Cell; Clone RMP1-14) plus GEM, or 5) anti-CSF1R plus anti-PD-1and GEM. Anti-CSF1R-antibody administration began on Day 12, withanti-PD-1 and GEM treatment beginning on Day 17. Tumors continued to beassessed at least twice per week for 20 days from the start ofanti-CSF1R antibody treatment.

The change in tumor size is shown by graphing mean tumor weight for allgroups at the end of the study. Treatment with either anti-CSF1Rantibody or anti-PD-1 antibody reduced tumor growth compared to the IgGcontrol. The combination of anti-CSF1R and anti-PD-1 resulted insignificantly reduced tumor growth compared to either anti-CSF1R oranti-PD-1 alone (P<0.05). P-values were calculated using unpaired,two-tailed t-test analyses of the calculated tumor volumes on day 32.(See FIG. 5.)

Example 5: Anti-CSF1R Antibody Treatment Increases the Frequency ofCytotoxic T Cells and Expression of PD-L1 in Multiple Mouse Tumor Models

Seven week old female C57BL/6 and BALB/c mice were purchased fromCharles River Laboratories (Hollister, Calif.) and were acclimated forat least three days before the start of the studies. The murinecolorectal carcinoma cell lines MC38 and CT26 were implantedsubcutaneously over the right flank of immunocompetent mice. MC38 wasinoculated at 0.5×10⁶ cells/100 μl/mouse, and CT26 was implanted at1.0×10⁶/200 μL/mouse. Prior to inoculation, the cells were cultured forthree passages in RPMI 1640 medium supplemented with 10%heat-inactivated Fetal Bovine Serum (FBS), 2 mM L-Glutamine. Cells weregrown at 37° C. in a humidified atmosphere with 5% CO₂. Upon reaching80-85% confluence, cells were harvested and resuspended at 5×10⁶ cellsper milliliter in cold serum-free RPMI 1640 (MC38) or RPMI/Matrigel(CT26).

Mice were monitored twice weekly following cell implantation for tumorgrowth. For tumor measurements, the length and width of each tumor wasmeasured using calipers and volume was calculated according to theformula: Tumor volume (mm³)=(width (mm)×length (mm))²/2. Beginning onDay 5 (CT26) or Day 7 (MC38), all tumors were measured, and mice wererandomly assigned to treatment groups. Mice were administered eitherMouse IgG1 (Clone MOPC-21) or anti-CSF1R antibody (cmFPA008). Studieswere concluded 21-24 days after inoculation, and tumors were excised andsnap frozen in liquid nitrogen.

To assess gene expression, QuantiGene Plex assays were utilized. Tumortissue from 7-10 mice per treatment group were lysed, and relativeexpression of multiple genes were assessed, including PTPRC (CD45),CD8a, CD4, GZMA, CSF1R, and CD274 (PD-L1). Gene expression values werenormalized against PPIB, GUSB, and HPRT, which were utilized ascontrols. Cd8a expression was further normalized against CD45 to assessrelative CD8 abundance or CD4 to examine the ratio of CD8 to CD4 cells.FIG. 8 shows the normalized expression values relative to IgG-treatedmice for each of MC38 and CT26 tumors.

Comparisons of relative gene expression were determined to bestatistically significant if P<0.05. P-values were calculated usingunpaired, two-tailed t-test analyses of the calculated gene expressionof anti-CSF1R antibody (cmFPA008)-treated tumors compared to IgGcontrol. Statistical significance is shown in FIG. 8 as follows: *p<0.05, ** p<0.01.

Example 6: Combination Therapy with an Anti-CSF1R Antibody and aPD-1/PD-L1 Inhibitor

Anti-CSF1R antibody (an antibody comprising heavy chain and light chainvariable regions of SEQ ID NOs: 53 and 60, respectively) areadministered in combination with an anti-PD-1 antibody at increasingdosages in subjects with a variety of tumor types, including NSCLC,melanoma, SCCHN, bladder cancer, and pancreatic cancer. The anti-CSF1Rantibody is administered at doses ranging from 1 mg/kg to 10 mg/kg. Theanti-CSF1R antibody and the anti-PD-1 antibody are dosed concurrentlyevery 2 weeks.

Anti-CSF1R antibody and anti-PD-1 antibody are administered to threesubsets of patients with melanoma: naïve (have never received eitherantibody), acquired resistance (have progressed after an initialanti-PD-1 antibody response), and de novo resistance (did not respond toPD-1/PD-L1 inhibit therapy).

Pre- and post-treatment core needle biopsies are obtained in a subset ofsubjects to evaluate potential changes in immune cells, stroma, andtumor cells after treatment. In addition to hematoxylin and eosinstaining to assess the overall cellularity of the tumor, specific assaysare used to monitor macrophage numbers and subtypes. Patients areadditionally monitored for overall response, immune-related response,and overall survival.

For some, most, or all patients, the number of CD8+ T cells increasesafter treatment with the combination and/or the number of Treg cellsdecreases after treatment with the combination. In addition, for some,most, or all patients, the number of tumor enhancing M2 macrophagesdecreases and the number of tumor suppressing M1 macrophages increasesafter treatment with the combination. Finally, for some, most, or allpatients, tumor necrosis increases after treatment with the combination.

Example 7: Summary of a Monotherapy and Combination Therapy ClinicalTrial with an Anti-CSF1R Antibody and an Anti-PD-1 Antibody

Anti-CSF1R antibody HuAB1 is given as a monotherapy and in combinationwith the anti-PD-1 antibody nivolumab in patients with selected advancedcancers and who have not previously received a CSF1R pathway inhibitorin an open-label, multicenter, dose escalation and dose expansion study.Nivolumab has previously been approved for use in melanoma, metastaticNSCLC, and in combination with ipilmumab, an anti-CTLA-4 antibody, forthe treatment of metastatic melanoma. For the combination arms of thestudy, HuAB1 and nivolumab will be given on Day 1 of each 14-daytreatment cycle; nivolumab will be given as an IV infusion over 30minutes first, with a 30-minute rest between 2 infusions, followed by a30-minute HuAB1 IV infusion.

The first phase of the study (Phase 1a) comprises two HuAB1 monotherapyreference cohorts (1aM1 and 1aM2) and three dose-escalation cohorts ofHuAB1 in combination with nivolumab (1aC1, 1aC2, and 1aC3). The secondphase of the study (Phase 1b) comprises eight cohorts (1b1 through 1b8)across six cancer types. Approximately 270 total patients will take partin the study, 30 in the first phase and 240 in the second phase with 30in each of the 8 cohorts of the second phase. Individual patients willbe enrolled in no more than one of the study arms 1aM, 1aC, or 1b. FIG.6 shows a schematic of the study design.

In Phase 1a, monotherapy patients in cohorts 1aM1 and 1aM2 are given 2mg/Kg or 4 mg/Kg HuAB1 once every 14 days (q2w). Combination therapycohorts 1aC1, 1aC2, and 1aC3 are given 1, 2, or 4 mg/Kg HuAB1 and 3mg/Kg nivolumab once every 14 days (q2w). Patients in the 1aM1 and 1aC1cohorts are treated for a total of two 14-day cycles within a 28-dayperiod, followed by the other cohorts. A 3 mg/Kg HuAB1 and 3 mg/Kgnivolumab cohort may also be included. In Phase 1a, patients may beincluded in either the monotherapy or combination therapy cohorts ifthey have a histologically or cytologically confirmed solid tumor thatis locally recurrent or metastatic and has progressed following standardtreatment or is not appropriate for standard treatment. Patients withany prior exposure to any PD-1 pathway targeting drug are excluded.

In Phase 1b, eight patient cohorts are treated, as follows.

Cohort 1b1: NSCLC (Anti-PD-1 Therapy Naïve, Second or Third Lines).

This cohort may include patients with histologically or cytologicallydocumented squamous or non-squamous NSCLC who present with Stage IIIB orIV disease (according to version 7 of the international association forthe Study of Lung Cancer Staging manual in Thoracic oncology) and withrecurrent or progressive disease following multi-modal therapy(radiation therapy, surgical resection or definitive chemoradiation) forlocally advanced or metastatic disease. It may include patients withprogression or recurrence during/after a platinum doublet-basedchemotherapy regimen for advanced or metastatic disease. Patients withany prior exposure to any PD-1 pathway targeting drug are excluded.

Cohort 1b2: NSCLC (Patients Refractory to Anti-PD-1 Targeting Drugs).

This cohort may include patients with histologically or cytologicallydocumented NSCLC who present with Stage IIIB locally advanced or StageIV disease, and patients with radiological evidence of diseaseprogression during treatment with a PD-1 pathway targeting drug that didnot produce a clinical response (i.e., neither CR nor PR) and withprogressive disease as the best response. In the context of this cohort,refractory patients are patients that have had no clinical responseafter receiving at least 2 doses of any PD-1 targeting drug. Patientsthat are intolerant to any PD-1 pathway targeting drug are excluded,where intolerance is defined as any treatment-related Grade 4 adverseevent, or any treatment-related Grade 2 or 3 adverse event that isunacceptable to the patient and persists despite standardcountermeasures.

Cohort 1b3: Melanoma (Anti-PD-1 Therapy Naïve)

This cohort may include patients with histologically or cytologicallydocumented Stage III or IV melanoma as per the American Joint Committeeon Cancer (AJCC) staging system who are either refractory to, intolerantto, or have refused, standard therapy for treatment of metastaticmelanoma. Included patients may demonstrate objective evidence ofdisease progression despite treatment with a BRAF inhibitor or may beBRAF wild-type. Patients with any prior exposure to any PD-1 pathwaytargeting drug, who are BRAF mutant, or whose BRAF mutational status isnot known or cannot be determined are excluded.

Cohort 1b4: Melanoma (Refractory or Relapsed on Anti-PD-1 TargetingDrug)

Patients in this cohort may have histologically or cytologicallydocumented unresectable Stage III or IV melanoma as per the AJCC stagingsystem. Included patents may show radiological evidence of diseaseprogression during treatment with a Checkpoint inhibitor or a PD-1targeting drug that did not produce a clinical benefit, or may show,while receiving treatment with a PD-1 targeting drug, progressivedisease as the best response or disease progression after an initialclinical benefit. In the context of this cohort, refractory patients arepatients that have had no clinical response after receiving at least 2doses of any PD-1 targeting drug. Included patients may demonstrateobjective evidence of disease progression despite treatment with a BRAFinhibitor or may be BRAF wild-type. Any prior anticancer therapyincluding dacarbazine, BRAF inhibitor (if BRAF V600 mutantion positive)and/or ipilimumab and palliative radiotherapy are completed at least 3weeks prior to study drug administration and treatment with a PD-1targeting drug is discontinued at least 6 weeks prior to first dose ofthe study drug. Patients that are intolerant to any PD-1 pathwaytargeting drug as defined above are excluded, as are pateints who areBRAF mutant or whose BRAF mutational status is either unknown or cannotbe determined.

Cohort 1b5: Squamous Cell Carcinoma of the Head and Neck (SCCHN) (SecondLine)

Patients with histologically or cytologically documented recurrent ormetastatic SCCHN (oral cavity, pharynx, larynx), stage III or IV and notamenable to local therapy with curative intent (surgery or radiationtherapy with or without chemotherapy) may be included in this cohort.Patients may also have progression or recurrence within 6 months of thelast dose of platinum therapy in the adjuvant (i.e. with radiation aftersurgery), primary (i.e., with radiation), recurrent, or metastaticsetting. Clinical progression after platinum therapy is an allowableevent for entry and is defined as progression of a lesion at least 10 mmin size that is amenable to caliper measurement (e.g., superficial skinlesion as per RECIST v1.1) or a lesion that has been visualized andphotographically recorded with measurements and shown to haveprogressed. Patients with prior exposure to an anti-PD-1 drug areexcluded.

Cohort 1b6: Pancreatic Cancer (Second Line)

Included patients may have histologically or cytologically documentedlocalized or metastatic adenocarcinoma of the pancreas, which has failed(or are not indicated for) standard therapy. Patients may also havereceived prior surgery, radiation therapy for the management of locallyadvanced or metastatic adenocarcinoma of the pancreas providing thatdisease progression has been documented. All toxicities should beresolved, and the last fraction of radiation treatment was completed atleast 4 weeks prior to first study drug administration. Patients withprior exposure to an anti-PD-1 drug are excluded.

Cohort 1b7: Colorectal Cancer (Third Line)

Included patients may have histologically or cytologically documentedadenocarcinoma of colon or rectum, and they may have metastaticcolorectal cancer with documented disease progression after the lastadministration of standard therapies or intolerance to standardtherapies (and approved therapies had to include a fluoropyrimidine,oxaliplatin, irinotecan, bevacizumab, and, if KRAS wild-type, cetuximabor panitumumab). Patients with prior exposure to an anti-PD-1 drug areexcluded.

Cohort 1b8: Malignant Glioma (First Recurrence)

Patients in this cohort may have histologically or cytologicallydocumented advanced World Health Organization (WHO) Grade IV malignantglioma (glioblastoma or gliosarcoma) and may have had previous treatmentwith surgery, radiotherapy and temozolomide. Patients may have adocumented first recurrence by diagnostic biopsy or contrast-enhancedMRI performed within 21 days of first study drug administration perResponse Assessment in Neuro-oncology (RANO) criteria. Patients areexcluded if they have received prior treatment with bevacizumab oranother VEGF or VEGF receptor targeting agent, more than 1 recurrence ofglioblastoma or gliosarcoma, or prior exposure to any PD-1 targetingdrug.

Monotherapy patients are administered HuAB1 as a 30 minute IV infusion.Combination therapy patients receive the nivolumab infusion first at adose of 3 mg/kg as a 30-minute IV infusion, on Day 1 of each 14-daytreatment cycle. They receive HuAB1 following the nivolumab infusion onDay 1 of each 14-day treatment cycle, with a 30-minute rest between thetwo infusions.

A biopsy at the tumor site is collected prior to Day 1 of the firstcycle of the study and again on Day 29. Patients are also assessed foroverall survival post-study, progression-free survival, and duration ofresponse for those patients with confirmed responses, based on thecriteria of RECIST v1.1. CT/MRI (chest, abdomen, pelvis, and brain) areperformed before Day 1, during treatment, and following the study, andmeasurements of tumor burden are taken. The primary response parameteris the objective response rate, which is the number of patients withcomplete or partial response divided by the total number of treatedpatients with measurable disease at baseline. Tumor response is assessedusing RECIST v1.1, Appendix F.

Example 8: Complete Clinical Trial Phase 1a and 1b Protocol-Monotherapyand Combination Therapy Clinical Trial with an Anti-CSF1R Antibody(HuAB1 Also Known as FPA008) and an Anti-PD-1 Antibody (Nivolumab) 1Introduction and Study Rationale Colony Stimulating Factor 1 Receptorand Tumor-Associated Macrophages

Macrophages are myeloid-derived cells that carry out a variety offunctions in the human body. They can colonize tissues (and tumors)through two distinct mechanisms: hematogenous seeding from circulatingmonocytes or local self-renewal in the form of tissue-residentmacrophages (Lavin, 2013). Recent studies have shown that macrophagesexert their physiological effect within, and play roles unique to, thetissues in which they are active (Lavin, 2014). Macrophage regulation iscomplex as these cells actively secrete and respond to multiple cytokineand chemokine gradients within their local environment.

Tumor-associated macrophages (TAMs) are among the most abundant immunecell types in the tumor microenvironment. Substantial evidence suggeststhat TAMs are polarized towards an anti-inflammatory phenotype (M2) thatinhibits anti-tumor immune responses (Noy, 2014) through both cell-cellcontact and soluble factors such as immunosuppressive cytokines.Consistent with this, increased levels of TAMs are associated with apoor prognosis in a majority of cancers (Komohara, 2014).

Following treatment with anti-CSF1R agents, the macrophages that havenot been depleted may be repolarized from an M2 immunosuppressive stateto an M1 anti-tumor state which would support T-cell responses. Thisconversion, associated with concurrent treatment modalities, such asanti-PD-1 treatment, could have an increased effect on reduction oftumor growth (Ruffell, 2015).

Response rates in ongoing PD-L1 studies have been shown to correlatewith the concentration of PD-1/PD-L1 in the tumor stroma (Tumeh, 2014).Of note, there is also a significant amount of macrophages in the tumorstroma as recruitment of monocytes into the tumor stroma leads to theirdevelopment into suppressive M2 macrophages. The association ofmonocytes and macrophages with PD-L1 has been shown to suppresstumor-specific T-cell immunity and correlate with poor survival inpatients. Predictably, blockade of monocyte-associated PD-L1 positivecells in vivo was demonstrated to improve tumor-specific T-cellimmunity. In vitro studies have also shown that activated monocytesexpressing PD-L1 demonstrate considerable prevention of tumor-specificT-cell proliferation, cytokine production, and cytotoxic potential(Kuang, 2009).

Colony stimulating factor 1 receptor (CSF1R) signaling plays afundamental role in the differentiation, maintenance, and function ofmacrophages and a subset of other myeloid lineage cells that includesmonocytes, and osteoclasts (Hamilton, 2013). The two known ligands forCSF1R are CSF1 and IL34. Both of these agonists bind to overlappingregions of CSF1R with similar affinity (Masteller, 2014), even thoughthey have little amino acid homology in common. Mice lacking CSF1R havedeficiencies in macrophages, underscoring the essential role of theCSF1R pathway in the biology of this cell type (Dai, 2002).Pharmacologic treatments that block CSF1R in cancer settings areexpected to reduce or reprogram TAMs and reduce immune suppression.Overall, this could produce a tumor microenvironment that is moreconducive to immune-based anti-cancer therapies.

HuAB1 is a recombinant, humanized immunoglobulin G4 (IgG4) monoclonalantibody that binds to human CSF1R. The interaction of HuAB1 and CSF1Rantagonizes the binding of both CSF1 and IL34 to CSF1R, therebypreventing receptor activation. HuAB1 inhibits both CSF1 andIL34-induced CSF1R phosphorylation in a cell line engineered tooverexpress CSF1R (CHO-CSF1R), demonstrating experimentally that HuAB1blocks the activation of ligand-induced CSF1R signaling pathways. HuAB1also inhibits CSF1 and IL34-induced proliferation and survival ofperipheral blood monocytes in vitro, demonstrating that HuAB1 inhibitsnot only the initiation of CSF1 and IL34 signaling pathways, but alsothe subsequent physiologic responses of primary human monocytes to theseligands.

Taken together, these and other emerging data suggest that blockingCSF1R with HuAB1 treatment could alleviate the immunosuppressive tumorenvironment that is generated by TAMs and could improve the efficacy ofimmune-based anti-cancer therapies.

PD-1

Programmed Cell Death-1 (PD-1; CD279) is a cell surface signalingreceptor that delivers inhibitory signals that regulate the balancebetween T-cell activation and tolerance by interacting with its ligands,PD-L1 (CD274; B7-H1) and PD-L2 (B7-DC/CD273). It is a 55 kD type Itransmembrane protein that is a member of the CD28 family of T-cellcostimulatory receptors, which also includes inducible co-stimulator(ICOS), cytotoxic T lymphocyte antigen-4 (CTLA-4), and B- andT-lymphocyte attenuator (BTLA) (Freeman, 2000). PD-1 contains anintracellular membrane proximal immunoreceptor tyrosine inhibitory motif(ITIM) and a membrane distal immunoreceptor tyrosine-based switch motif(ITSM). PD-1 is primarily expressed on activated T cells, B cells, andmyeloid cells (Nishimura, 2001a). Its ligands, PD-L1 and PD-L2, havebeen shown to down-regulate T-cell activation upon binding to PD-1 inboth murine and human systems (Carter, 2002; Latchman, 2001). PD-1delivers a negative signal by the recruitment of SHP-2 to thephosphorylated tyrosine residue in the ITSM in its cytoplasmic region(Chemnitz, 2004; Sheppard, 2004).

Evidence for a negative regulatory role of PD-1 comes from studies ofPD-1-deficient mice, which develop various autoimmune phenotypes,including dilated cardiomyopathy and a lupus-like syndrome witharthritis and nephritis (Nishimura, 1999; Nishimura, 2001b; Okazaki,2003). The emergence of these autoimmune phenotypes is dependent on thegenetic background of the mouse strain; many of these phenotypes emergeat different times and show variable penetrance. In addition to thephenotypes of null mutations, PD-1 inhibition by antibody-mediatedblockade in several murine models has been found to play a role in thedevelopment of autoimmune diseases such as encephalomyelitis,graft-versus-host disease, and type I diabetes (Ansari, 2003; Blazar,2003; Salama, 2003). Taken together, these results suggest that PD-1blockade has the potential to activate anti-self T-cell responses, butthese responses are variable and dependent upon various host geneticfactors. Thus, PD-1 deficiency or inhibition is not accompanied by auniversal loss of tolerance to self-antigens.

The PD-1 targeting agent, nivolumab has been clinically tested inseveral tumor types including NSCLC, melanoma, and renal cell carcinoma(RCC) as a single agent or in combination with other treatments. Some ofthe efficacy data from the nivolumab Investigator's Brochure (IB) areshown in Table 1, below. Nivolumab as a single agent has remarkabledurable efficacy in a subpopulation of patients. The enhanced effect ofnivolumab combinations suggests the potential for opportunities withfurther benefits for patients as a combination regimen with otheruntested agents.

Nivolumab is currently FDA-approved for unresectable or metastaticmelanoma and disease progression following ipilimumab and, if BRAF V600mutation positive, a BRAF inhibitor. It is also approved for metastaticsquamous non-small cell lung cancer (NSCLC) with progression on or afterplatinum-based chemotherapy.

TABLE 1 Summary of nivolumab clinical efficacy data in melanoma, NSCLC,and RCC Study Study Tumor Response Number Drugs Type ORR DOR OSMDX1106-03 Nivolumab NSCLC 17% 17 months 24% @ 24 mo CA209012 NivolumabNSCLC 30% NR — Nivolumab + ipilimumab NSCLC 13-20%    NR — Nivolumab +chemotherapy NSCLC 33-47%    25.4-45 weeks — Nivolumab + erlotinib NSCLC19% NR — CA209017^(a) Nivolumab NSCLC — —  9.2 months CA209063^(b)Nivolumab NSCLC 14.5%  NR — MDX1106-03 Nivolumab Melanoma 31% >6 months48% @ 24 mo CA209004 Nivolumab + ipilimumab Melanoma 42-43%    — 85% @12 mo CA209037^(c) Nivolumab Melanoma 31.7%  — — CA209038 NivolumabMelanoma 18-32%    — — MDX1106-03 Nivolumab RCC 21% >6 months 48% @ 24mo CA209010 Nivolumab RCC 20-22%    — 18.2 months CA209016 Nivolumab +ipilimumab RCC 43-48%    — — Nivolumab + sunitinib RCC 52% — —Nivolumab + pazopanib RCC 45% — — ^(a)Opdivo Package Insert, 2015^(b)Rizvi, 2015 ^(c)Weber, 2015

1.1 Rationale for HuAB1 and Nivolumab Combination Therapy

HuAB1 is a humanized monoclonal antibody directed against CSF1R.Targeting the CSF1R pathway with antibodies or small molecule inhibitorshas been shown to be effective in syngeneic mouse tumor models. In anMC38 colon adenocarcinoma model in mice, a CSF1R targeting antibodyresulted in a significant reduction of TAMs, which was accompanied by apositive shift of the CD8⁺ to CD4⁺ ratio towards cytotoxic CD8⁺ T cells.In a recent clinical study, RG7155 (a CSF1R targeting antibody) wastested in patients with solid tumors and was shown to substantiallyreduce CSF1R⁺CD163⁺ macrophages in tumors (Ries, 2014). This reductionin macrophages was also associated with a decrease in FOXP3⁺ regulatoryT cells. These data suggest that other immune effector cells wereindirectly influenced by CSF1R blockade. In a mouse proneuralglioblastoma multiforme (GBM) model, small molecule inhibition of CSF1Rsignificantly increased survival and regressed established tumors(Pyonteck, 2013). In this model, TAMs were not depleted, but insteadconverted to a more pro-inflammatory phenotype in the presence of CSF1Rinhibition.

In an orthotopic pancreatic ductal adenocarcinoma (PDAC) model, CSF1Rpathway blockade with a small molecule or an anti-CSF1 antibodyselectively decreased immunosuppressive TAMs, subsequently reducingimmunosuppression. This decrease in immunosuppressive TAMs enabled theremaining pro-inflammatory TAMs to support antigen presentation andbolster the anti-tumor T-cell response (Zhu, 2014). This, in turn, ledto an increased interferon response that upregulated T-cell checkpointinhibitors, including PD-L1, on tumor cells. This counter-regulationserved to limit the anti-tumor T-cell response through engagement of theT-cell inhibitor PD-1. Importantly, anti-PD-1 treatment was able toovercome the PD-L1-mediated inhibition. Targeting PD-1 as a single agentshowed limited efficacy in restraining PDAC tumor growth, but combiningPD-1 blockade with CSF1R inhibition potently elicited tumor regressioneven in large, established tumors.

Together, these data suggest that reprogramming the TAM compartment intumors via HuAB1-mediated CSF1R blockade could reduce immunosuppressiveTAMs in the tumor microenvironment and improve the efficacy ofcheckpoint-based immunotherapies such as nivolumab.

1.2 Rationale for HuAB1/Nivolumab Combination Therapy in Selected TumorTypes

TAMs can potently suppress anti-tumor immune responses. CSF1R is a cellsurface receptor that is expressed on TAMs and regulates their survivaland function. CSF1R-blocking antibodies have been shown to reduce TAMsin both murine and human tumors (Ries, 2014). TAMs are present in manyhuman cancers suggesting that CSF1R blocking antibodies, such as HuAB1,could be used to treat multiple tumor types. In addition, TAMs have beenshown to correlate with poor prognosis in a number of cancers, includinglung, pancreatic, head and neck, and melanoma, among others (Komohara,2014). Furthermore, analysis of The Cancer Genome Atlas shows highcorrelation of CSF1R with PD-1/PD-L1 co-expression, and T-cellsignatures in head and neck, lung, and melanoma cancers, as well asothers. In preclinical models, CSF1R inhibition has also been shown toalter macrophage polarization and block glioma progression (Pyonteck,2013). CSF1R blockade also reduces TAMs and synergizes with PD-1 andCTLA4 checkpoint blockade in pancreatic cancer models (Zhu, 2014). Itwas also shown that colorectal tumor cells express relatively lowerlevels of PD-L1 compared to melanoma or lung cancers and that the levelsof PD-L1 observed are present on infiltrating myeloid cells (Llosa,2015).

Nivolumab is currently being tested in multiple tumor types, includingall of the tumor types proposed for the Phase 1b portion of this study.As the nivolumab data mature, they will help inform the Phase 1bexpansion of this study into selected tumor types.

In addition to the ongoing studies, nivolumab has been approved for usein melanoma and squamous NSCLC. The melanoma approval was based on theresults of the CheckMate 037 study. In this study, the efficacy andsafety of nivolumab were compared with investigator's choice ofchemotherapy (ICC) as a second-line or later-line treatment in patientswith advanced melanoma. In this study, 272 patients were randomized tonivolumab and 133 to ICC. Confirmed objective responses were reported in32% of the first 120 patients in the nivolumab group versus 11% ofpatients in the ICC group. Grade 3-4 adverse events attributed tonivolumab included increased lipase, increased ALT, anemia, and fatigue(1% each); for ICC, these included neutropenia (14%), thrombocytopenia(6%), and anemia (5%). There were also Grade 3-4 drug-related SAEs in 5%of nivolumab-treated patients and 9% of patients in the ICC group. Notreatment-related deaths occurred (Weber, 2015).

The approval in NSCLC for nivolumab was based on the results of theCheckMate 017 and CheckMate 063 studies. CheckMate 017 enrolled patientswith metastatic squamous NSCLC who had experienced disease progressionduring or after one prior platinum doublet-based chemotherapy regimen.OS with nivolumab treatment was 9.2 months, versus 6.0 months withdocetaxel (Opdivo Package Insert, 2015). CheckMate 063 assessed theactivity of nivolumab in patients with advanced, refractory, squamousNSCLC. The study enrolled and treated 117 patients. Of these, 14.5% ofpatients had an objective response as assessed by an independentradiology review committee and 26% had stable disease. Median time toresponse was 3.3 months and median duration of response was not reached.Of the 17 responses, 77% were ongoing at the time of analysis. Of the117 patients, 17% reported Grade 3-4 treatment-related AEs, including:fatigue (4%), pneumonitis (3%), and diarrhea (3%). There were twotreatment-associated deaths caused by pneumonia and ischemic stroke thatoccurred in patients with multiple comorbidities in the setting ofprogressive disease (Rizvi, 2015).

The data reported above support investigation of HuAB1 in combinationwith nivolumab in melanoma, NSCLC, head and neck, pancreatic,colorectal, and glioma cancers.

1.3 Rationale for Starting Dose for HuAB1 Monotherapy and CombinationDose Escalation

The Sponsor has already initiated a first-in-human Phase 1 clinicalstudy designed in 3 parts to evaluate safety, PK and biomarkers ofsingle agent HuAB1 in healthy volunteers and rheumatoid arthritis (RA)patients (Study FPA008-001). In Parts 1 and 2 of this study, HuAB1 wastested in healthy volunteers at doses of 0.2, 1, 3, and 10 mg/kg bodyweight. In the healthy volunteer group, at 1 mg/kg, 7 subjects receiveda single dose and 5 subjects received 2 doses; at 3 mg/kg, 10 subjectsreceived a single dose and 2 subjects received 2 doses; at 10 mg/kg, 6subjects received a single dose of HuAB1. Multiple-dose cohorts weregiven doses 14 days apart and all subjects were followed up for doselimiting toxicities (DLTs) through a 28-day window.

As of Sep. 23, 2014, 48 subjects have completed Parts 1 and 2 of thestudy. No DLTs were reported in Parts 1 or 2. All adverse events (AEs)were Grade 1 or 2 and self-limited with the most common HuAB1treatment-related toxicities being pruritus, eyelid edema along withfacial swelling, fatigue, and headache. Temporary elevations in serumenzymes such as creatinine kinase (CK), lactate dehydrogenase (LDH),alanine aminotransferase (ALT) and aspartate aminotransferase (AST) wereobserved.

In the ongoing Part 3 arm of the Phase 1 study, RA patients who did notrespond to disease-modifying anti-rheumatic drugs (DMARDs) areparticipating in an open-label study at different dose levels of HuAB1at 1, 3, and 6 mg/kg body weight. These patients are required to be on astable weekly dose of methotrexate before and during the study and willreceive 2 doses of HuAB1, 14 days apart. In addition to other analyses,the patients are being followed for safety, pharmacokinetics (PK), andpharmacodynamics (PD) after the 2-dose regimen.

In summary, 36 healthy volunteers and 6 RA patients have received HuAB1to date, no DLTs were reported in Parts 1 or 2, and no significanttreatment-related toxicities have been reported from RA patients in the1 mg/kg or 3 mg/kg dose levels. The safety profile of nivolumab is wellestablished and supported by the recent U.S. marketing authorizationsfor the treatment of melanoma and squamous NSCLC. The number of subjectsdosed, the dose levels evaluated, and the current overall AE profile ofHuAB1 and nivolumab support concurrent initiation of the 2 mg/kg HuAB1monotherapy and 1 mg/kg HuAB1 with 3 mg/kg nivolumab combination therapycohorts in this study.

The Phase 1a portion of this study will consist of a two-stepmonotherapy dose escalation of HuAB1 at 2 mg/kg followed by 4 mg/kgHuAB1. There will also be a three-step dose escalation of a fixed doseof 3 mg/kg nivolumab in combination with 1 mg/kg HuAB1, followed by 2mg/kg HuAB1, then 4 mg/kg HuAB1.

The 4 mg/kg HuAB1 monotherapy cohort will be opened after the 28-day DLTperiod clears in the 2 mg/kg HuAB1 monotherapy cohort. The 2 mg/kgHuAB1/nivolumab combination cohort will only start after the DLT periodclears in the 1 mg/kg HuAB1/nivolumab combination cohort and 2 mg/kgHuAB1 monotherapy cohort. The 4 mg/kg HuAB1/nivolumab combination cohortwill be opened after the DLT period clears in the 1 mg/kg and 2 mg/kgHuAB1/nivolumab combination cohorts and in the 2 mg/kg and 4 mg/kg HuAB1monotherapy cohorts. The dose escalation schematic is shown in FIG. 7.

All patients will be on a continuous dosing schedule every 14 days andfollowed up until disease progression, unacceptable toxicity orwithdrawal of consent.

1.4 Rationale for 30-Minute Infusion Administration for Each Study Drug

Long infusion times, especially when multiple agents are administeredsequentially to an individual, place a burden on patients and treatmentcenters.

HuAB1, a CSF1R inhibitor, has been dosed over 30 minutes in studies inhealthy volunteers and also for patients with RA.

Nivolumab has been administered safely over 60 minutes at doses rangingup to 10 mg/kg over extended treatment durations. In Study CA209010, (aPhase 2, randomized, double blinded, dose-ranging study of nivolumab insubjects with advanced/metastatic clear-cell RCC), a dose associationwas observed for infusion site reactions and hypersensitivity reactions(1.7% at 0.3 mg/kg, 3.7% at 2 mg/kg and 18.5% at 10 mg/kg). All eventswere Grade 1 or 2 and manageable. An infusion duration of 30 minutes for3 mg/kg nivolumab (30% of the dose provided at 10 mg/kg) is not expectedto present more serious safety concerns compared to the prior experienceof 10 mg/kg nivolumab infused over 60 minutes.

Overall, infusion reactions, including high-grade hypersensitivityreactions, have been uncommon across nivolumab and HuAB1 clinicalstudies. Furthermore, a 30 minute break following the nivolumab infusionin the combination cohorts will ensure time for appropriate safetymonitoring before the start of the HuAB1 infusion. Overall, a variationin the safety profile is not anticipated with a 30-minute infusion ofnivolumab or HuAB1 either alone or in combination.

1.5 Research Purposes

The purpose of the Phase 1a arm of this trial is to evaluate safety andtolerability following administration of HuAB1 monotherapy as well as incombination with nivolumab in patients with advanced cancers and toidentify the recommended dose (RD) of HuAB1 for the Phase 1b combinationarm of this study.

The purpose of the Phase 1b arm of this trial is to further characterizethe safety profile of HuAB1 in combination with nivolumab and toevaluate the clinical benefit at the RD of HuAB1/nivolumab combinationtherapy in patients with selected, advanced cancers.

1.6 Objectives

1.6.1 Phase 1a Objectives 1.6.1.1 Primary

To assess the safety and tolerability of HuAB1 as monotherapy

To assess the safety and tolerability of HuAB1 in combination withnivolumab

To determine the RD of HuAB1 in combination with a fixed dose ofnivolumab

1.6.1.2 Secondary

To characterize the PK profile of HuAB1

To characterize the PK peak and trough concentration profile ofnivolumab when administered in combination with HuAB1

To characterize the PD profile of HuAB1 and nivolumab

To characterize the immunogenicity of HuAB1 and nivolumab

To assess the association of selected biomarker measures and clinicalefficacy measures using pre-treatment and on-treatment tumor biopsies

1.6.1.3 Exploratory

To further characterize the PD profile of HuAB1 and nivolumab

1.6.2 Phase 1b Objectives 1.6.2.1 Primary

To evaluate the clinical benefit of HuAB1 in combination with nivolumabin patients with selected advanced cancers through the analysis ofobjective response rate (ORR).

To evaluate the safety and tolerability of HuAB1 in combination withnivolumab in patients with selected advanced cancers treated at the RD

1.6.2.2 Secondary

To evaluate the clinical benefit of HuAB1 in combination with nivolumabin patients with selected advanced cancers through the analysis ofoverall survival (OS), duration of response (DOR), and progression freesurvival (PFS)

To characterize the PK profile of HuAB1

To characterize the PK peak and trough concentration profile ofnivolumab when administered in combination with HuAB1

To characterize the PD profile of HuAB1 and nivolumab

To characterize the immunogenicity of HuAB1 and nivolumab

To assess the association of selected biomarker measures and clinicalefficacy measures using pre-treatment and on-treatment tumor biopsies

1.6.2.3 Exploratory

To further characterize the PD profile of HuAB1 and nivolumab

1.7 Product Development Background

1.7.1 Mechanism of Action 1.7.1.1 HuAB1

HuAB1 is a recombinant, humanized IgG4 monoclonal antibody that binds tohuman CSF1R. Binding of HuAB1 to CSF1R antagonizes its natural ligands,CSF1 and IL34, thereby preventing activation of CSF1R. HuAB1 contains asingle amino acid substitution in the hinge region to prevent hemi-dimerexchange.

HuAB1 inhibits both CSF1 and IL34-induced CSF1R phosphorylation in acell line engineered to overexpress CSF1R (CHO-CSF1R), demonstratingthat HuAB1 blocks the activation of ligand-induced CSF1R signalingpathways. HuAB1 also inhibits CSF1 and IL34-induced proliferation andsurvival of peripheral blood monocytes in vitro, demonstrating thatHuAB1 inhibits not only the initiation of CSF1 and IL34 signalingpathways, but also the subsequent physiologic responses of primary humanmonocytes to these ligands.

CSF1R is expressed on cells of the monocyte/macrophage lineage andsignaling through CSF1R via its ligands, CSF1 and IL34, supportsdifferentiation, maintenance, and function of monocytes, macrophages,and osteoclasts. TAMs are among the most abundant immune cell types inthe tumor microenvironment. Substantial evidence suggests that TAMs arepolarized towards an anti-inflammatory phenotype and through both cellsurface inhibitors and soluble factors, such as immunosuppressivecytokines, play a major role in inhibiting anti-tumor immune responses(Noy, 2014). CSF1 is a major survival factor for TAMs and targetingCSF1R through HuAB1 should reduce TAM-mediated immune suppressionresulting in strengthening the anti-tumor response to immunotherapy.Therefore, a drug that inhibits CSF1R should limit theimmune-suppressive influence of TAMs on the tumor microenvironment andcould be complementary and augment current cancer therapies.

Since HuAB1 does not cross-react to mouse CSF1R, a surrogate antibody,cmHuAB1, was developed that binds and blocks mouse CSF1R with similarpotency observed for HuAB1 against human CSF1R. cmHuAB1 contains ratvariable regions and a mouse IgG1 Fc region. Binding of cmHuAB1 to mouseCSF1R was demonstrated in a direct binding enzyme-linked immunosorbentassay (ELISA), and cmHuAB1 inhibitory activity was demonstrated by itsability to inhibit CSF1-induced and IL34-induced proliferation of aCSF1/IL34-dependent cell line (mNFS60). The EC₅₀ value for cmHuAB1binding to mouse CSF1R is 2.4 ng/mL, and the IC₅₀ values for inhibitionof mouse CSF1-induced and mouse IL34-induced proliferation/survival ofmNFS60 cells are 32.9 and 9.1 ng/mL, respectively.

1.7.1.2 Nivolumab

Cancer immunotherapy rests on the premise that tumors can be recognizedas foreign rather than as self and can be effectively attacked by anactivated immune system. An effective immune response in this setting isthought to rely on immune surveillance of tumor antigens expressed oncancer cells that ultimately results in an adaptive immune response andcancer cell death. Meanwhile, tumor progression may depend uponacquisition of traits that allow cancer cells to evadeimmunosurveillance and escape effective innate and adaptive immuneresponses (Dunn, 2002; Jemal, 2011; Pardoll, 2003; Zitvogel, 2006).Current immunotherapy efforts attempt to break the apparent tolerance ofthe immune system to tumor cells and antigens by either introducingcancer antigens by therapeutic vaccination or by modulating regulatorycheckpoints of the immune system.

T-cell stimulation is a complex process involving the integration ofnumerous positive as well as negative co-stimulatory signals in additionto antigen recognition by the T-cell receptor (TCR) (Greenwald, 2004).Collectively, these signals govern the balance between T-cell activationand tolerance. PD-1 signaling has been shown to inhibit CD28-mediatedupregulation of IL-2, IL-10, IL-13, interferon-□ amma (IFN-γ) andBcl-xL. PD-1 signaling has also been noted to inhibit T-cell activation,and expansion of previously activated cells. Evidence for a negativeregulatory role of PD-1 comes from studies of PD-1 deficient mice, whichdevelop a variety of autoimmune phenotypes (Sharpe, 2007). These resultssuggest that PD-1 blockade has the potential to promote anti-self T-cellresponses, but these responses are variable and dependent upon varioushost genetic factors. Thus, PD-1 deficiency or inhibition is notaccompanied by a universal loss of tolerance to self antigens.

In vitro, nivolumab binds to PD-1 with high affinity (EC₅₀ 0.39-2.62nM), and inhibits the binding of PD-1 to its ligands, PD-L1 and PD-L2(IC₅₀ □ 1 nM). Nivolumab binds specifically to PD-1 and not to relatedmembers of the CD28 family such as CD28, ICOS, CTLA-4 and BTLA. Blockadeof the PD-1 pathway by nivolumab results in a reproducible enhancementof both proliferation and IFN-γ release in a mixed lymphocyte reaction(MLR). Using a cytomegalovirus (CMV) re-stimulation assay with humanperipheral blood mononuclear cells (PBMCs), the effect of nivolumab onantigen-specific recall response is indicative of nivolumab-augmentedIFN-γ secretion from CMV-specific memory T cells in a dose-dependentmanner versus an isotype-matched control. In vivo blockade of PD-1 by amurine analog of nivolumab enhances the anti-tumor immune response andresults in tumor rejection in several immunocompetent mouse tumor models(MC38, SA1/N, and PAN02) (Wolchok, 2009).

1.7.2 Preclinical Summary 1.7.2.1 HuAB1

The ability of cmHuAB1 to inhibit cancer growth in vivo was studied inan MC38 colon cancer model in immune-competent mice. These mice wereselected to allow for the establishment of an intact tumor-immuneinteraction. Treatment with cmHuAB1 began when tumors reachedapproximately 100 mm³. Mice were treated once per week byintraperitoneal injection of cmHuAB1 at 30 mg/kg, and the tumor growthwas compared to mice treated with albumin alone. cmHuAB1 significantlyreduced the growth of MC38 tumors compared to control-treated mice. Flowcytometry analysis of control mice showed that the CD11b⁺ myeloidcompartment in MC38 tumors was dominated by CD206⁺ macrophages. CD206 isa marker of immunosuppressive M2 macrophages. These CD206⁺ M2immunosuppressive macrophages were significantly reduced upon treatmentwith cmHuAB1. The reduction of M2 macrophages was accompanied by anincrease in CD8⁺ cytotoxic T cells relative to total CD4⁺ T cells orregulatory T cells defined as CD4⁺CD25^(high) cells. These data suggestreduction of immunosuppressive macrophages by cmHuAB1 results in a shifttowards a greater cytotoxic T cell response in the tumor.

The PK profile of HuAB1 is complex and characterized by nonlinearclearance that is likely mediated by binding to CSF1R on cells. Asmonocyte and macrophage cells are dependent on CSF1R for viability,these target-bearing cells are reduced in number following HuAB1treatment, resulting in a decrease of target-mediated clearance. Astarget-mediated clearance becomes saturated at high or repeat doses,HuAB1 clearance is similar to other human IgG antibodies.

Three PD biomarkers correlate with HuAB1 exposure in nonclinicalstudies: CSF1 serum levels, circulating CD16-positive peripheral bloodmonocytes (CD16⁺ monocytes), and serum markers of bone resorption(Trap5b and CTX). CSF1 serum levels rapidly rise and CD16⁺ monocytelevels rapidly fall in a dose-dependent manner that correlates closelywith HuAB1 plasma concentration. Saturation of the PD response isachieved at a low dose of HuAB1 (3 mg/kg weekly) in cynomolgus monkeys.The half-maximal response (IC₅₀) for reduction of CD16⁺ monocytes occursat a serum concentration of approximately 3 μg/mL and the maximalresponse occurs at approximately 10 μg/mL. The level of CD16-negative(CD16⁻) monocytes does not change with exposure to HuAB1.

In the in vivo toxicology studies in cynomolgus monkeys, HuAB1 wasgenerally well tolerated. Test article-related findings includedclinical observations, hematology and clinical chemistry changes, andhistopathological changes. The majority of these observations wereconsidered non-adverse. The most prominent clinical observation wasreversible periorbital edema, seen after prolonged exposure to HuAB1.The onset of the edema did not show a clear relationship to exposurelevels, but edema resolved after systemic clearance of the drug.Periorbital edema is a known side effect of drugs affecting the CSF1pathway (Cassier, 2014; Ries, 2014). The main hematologic change was areversible decrease in circulating CD16⁺ monocytes, which was considereda PD effect. HuAB1-related clinical chemistry effects includedreversible increased ALT, AST, CK, and LDH serum levels. Theselaboratory abnormalities were not associated with any histopathologicalevidence of liver, cardiac, or muscle tissue injury. Additionally,cardiac troponin, skeletal troponin (SkTnI), myoglobin, and aldolase didnot show any changes further confirming the lack of any liver or muscleinjury. The increased serum levels are attributed to diminishedclearance of ALT, AST, CK, and LDH molecules from serum due to a reducednumber of liver Kupffer cells (Radi, 2011). Accordingly, ALT, AST, CK,and LDH elevations are considered non-toxic and an indirect PD effect ofHuAB1 exposure.

A noteworthy histopathological finding was the reversible expansion ofthe submucosal collagen fibers by clear space and varying amounts of ablue, granular extracellular matrix (ECM) in a variety of tissues. Thischange was neither associated with inflammatory cells nor with any signof degeneration or other alteration of the collagen fibers, fibroblasts,or the smooth muscle cells within the area of expansion. A similarobservation was also seen in op/op mice that lack functional CSF1. Thereduction of tissue macrophages is the likely cause of the observedaccumulation of ECM due to a decreased clearance of glycosaminoglycans,especially hyaluronic acid, that are prominent in connective tissue andare normally catabolized by macrophages (Radi, 2009). This change isalso considered to be an indirect PD effect of HuAB1.

Cardiac troponin I was below the limit of quantitation (LOQ) in allsamples except for one female monkey in the 150 mg/kg group at Day 28.This animal did have a corresponding microscopic finding in the heart.While elevations of cardiac troponin I are highly specific formyocardial injury, the level detected in this monkey (0.26 ng/mL) wasmarginally above the assay LOQ (0.20 ng/mL) and much lower than whatwould be expected for an adverse cardiac event.

The no-observable-adverse-effect level (NOAEL) for HuAB1 was determinedto be 100 mg/kg when administered for 13 weekly doses to cynomolgusmonkeys, which provides a 32-fold safety factor based on body surfacearea calculation for the starting dose of 1 mg/kg in humans.

The minimum anticipated biological effect level (MABEL) was evaluated toguide starting dose decisions in healthy volunteers in thefirst-in-human study. The PD markers identified as representative of abiological effect were changes in CD16⁺ monocyte levels, elevation ofplasma CSF1, and elevation of serum ALT, AST, CK, and LDH. The lowestHuAB1 plasma concentration at which a biological effect occurred foreach marker ranged from 5 μg/mL to 105 μg/mL, and the HuAB1 dose thatcorresponded to 5 μg/mL at the maximum serum concentration (C_(max)) wasestimated to be 0.2 mg/kg, the recommended starting dose in healthyvolunteers.

1.7.2.2 Nivolumab

Nivolumab has been shown to bind specifically to the human PD-1 receptorand not to related members of the CD28 family, such as ICOS, CTLA-4, andBTLA (Nivolumab IB, 2014). Nivolumab inhibits the interaction of PD-1with its ligands, PD-L1 and PD-L2, resulting in enhanced T-cellproliferation and IFN-γ release in vitro (Velu, 2009; Nivolumab IB,2014). Fluorescent-activated cell sorter (FACS) analysis confirmed thatnivolumab binds to transfected Chinese hamster ovary (CHO) and activatedhuman T cells expressing cell surface PD-1 and to cynomolgus monkeyPD-1, but not to rat or rabbit PD-1 molecules. Nivolumab has also beenshown to bind to PD-1 on virus-specific CD8⁺ T cells from chronicallyinfected hepatitis C virus patients (Kaufmann, 2008; Rutebemberwa,2008).

PD-1 inhibition in an MLR resulted in a reproducibleconcentration-dependent enhancement of IFN-γ release in the MLR up to 50μg/mL. No effect was observed with a human IgG4 isotype control or CD4⁺T cells and dendritic cell (DC) controls (Wang, 2014).

In intravenous (IV) repeat-dose toxicology studies in cynomolgusmonkeys, nivolumab was well tolerated at doses up to 50 mg/kg,administered weekly for 5 weeks, and at doses up to 50 mg/kg,administered twice weekly for 27 doses. Nivolumab-related findings werelimited to a reversible decrease of 28% in triiodothyronine (T₃) amongthe females administered 27 doses of 50 mg/kg nivolumab. Nocorresponding changes in the level of thyroxine (T₄),thyroid-stimulating hormone (TSH), or histologic changes in the thyroidwere observed. While nivolumab alone was well tolerated in cynomolgusmonkeys, combination studies have highlighted the potential for enhancedtoxicity when combined with other immunostimulatory agents (NivolumabIB, 2014).

Ipilimumab (BMS-734016), an anti-CTLA-4 monoclonal antibody (mAb) thatblocks the down-regulation of T-cell activation, was used in combinationwith nivolumab to investigate the effects of concurrent inhibition ofthe PD-1 and CTLA-4 receptors in nonhuman primates (Nivolumab IB, 2014).Although gastrointestinal (GI) toxicity has not been observed incynomolgus monkeys treated with nivolumab alone, dose-dependent GItoxicity was evident in cynomolgus monkeys treated weekly for 4 weekswith a combination of nivolumab+ipilimumab at combinations of 10 and 3mg/kg and 50 and 10 mg/kg, respectively. GI effects have also beenobserved at a low incidence after ipilimumab administration (NivolumabIB).

In addition, an enhanced pre- and post-natal development (ePPND) studyin pregnant cynomolgus monkeys with nivolumab was conducted (NivolumabIB, 2014). Administration of nivolumab at up to 50 mg/kg every 2 weekswas well tolerated by pregnant monkeys; however, nivolumab wasdetermined to be a selective developmental toxicant when administeredfrom the period of organogenesis to parturition at ≥10 mg/kg (area underthe concentration-time curve [AUC] from time zero to 168 hours[AUC(0-168 h)] 117,000 μg·h/mL). Specifically, increased developmentalmortality (including late gestational fetal losses and extremeprematurity with associated neonatal mortality) was noted in the absenceof overt maternal toxicity. There were no nivolumab-related changes insurviving infants tested throughout the 6-month postnatal period.Although the cause of these pregnancy failures was undetermined,nivolumab-related effects on pregnancy maintenance are consistent withthe established role of PD-L1 in maintaining fetomaternal tolerance inmice (Habicht, 2007).

1.7.3 Clinical Summary 1.7.3.1 HuAB1 1.7.3.1.1 Ongoing Study Summary ofHuAB1

HuAB1 is currently being evaluated in a double-blind, randomized,placebo-controlled first-in-human trial designed in 3 parts to studysafety, PK, and PD in healthy volunteers and RA patients. The first twoparts of the study were conducted in healthy volunteers and have beencompleted. In Part 1, 8 healthy volunteers were randomized (3:1) toreceive a single IV infusion of HuAB1 or placebo, per dose cohort of0.2, 1, 3, or 10 mg/kg. In Part 2, 8 healthy volunteers were randomized(3:1) to receive 2 doses of HuAB1 or placebo administered 14 days apart,at 1 mg/kg or 3 mg/kg. Part 3 of the study will evaluate HuAB1 in RApatients and is currently ongoing. The data for Parts 1 and 2 aresummarized below.

1.7.3.1.2 Clinical Pharmacology Summary of HuAB1

The PK of HuAB1 was evaluated by measuring systemic drug levels overtime in all 36 subjects who received HuAB1 in Parts 1 and 2. Bloodsamples for determination of serum HuAB1 concentrations were collectedpre-dose and at various time points up to 112 days (for Part 1) or 98days (for Part 2) post-first dose. In addition, blood samples fordetermination of anti-HuAB1 antibodies were collected pre-dose and atvarious time points from Day 15 to Day 85 (for Part 1) or Day 15 to Day99 (for Part 2).

Following a single administration of HuAB1 at 0.2, 1, 3, and 10 mg/kg,total clearance decreased with increasing dose and ranged from 38.7 to2.55 mL/day/kg. The total clearance of 2.55 mL/day/kg at 10 mg/kg iswithin the range for a typical human IgG monoclonal antibody. TheC_(max) increased proportionally with dose, but the AUC did not.Following 2 doses given 14 days apart, there was no accumulation at 1mg/kg. However, when the dose increased to 3 mg/kg, a mean of 1.60-folddrug accumulation was observed between the first and the second dose forthe AUC from Day 1 to Day 15, while minimum accumulation was observedfor C_(max) at the same dose level. The observed PK data suggested thatCSF1R expressed on monocyte/macrophage lineage and other cell typescontributed to target-mediated clearance of HuAB1. As monocyte andmacrophage cells are dependent on CSF1R for viability, thesetarget-bearing cells are reduced in number following HuAB1 treatment,resulting in a decrease of target-mediated clearance. Oncetarget-mediated clearance is saturated at high or repeat doses, HuAB1clearance is similar to other human IgG antibodies.

Immunogenicity of HuAB1 was assessed using a validatedelectrochemiluminescence assay (ECLA) that measured total anti-HuAB1antibodies in serum. The limit of detection (sensitivity) of the assaywas 39.1 ng/mL. Three subjects in cohort 2 (1 mg/kg single dose) hadtrace positive antibody titers, resulting in 8.3% incidence (3 of 36subjects that received HuAB1). The trace positive antibody titers werefirst observed on Day 15 for 2 subjects and on Day 57 for 1 subject. Twosubjects still had ADA-positive titers on Day 85 (the last time pointtested). The presence of ADAs had negligible impact on HuAB1 exposure,if any, when compared to the subjects without ADAs in the same dosecohort, and there were no associated clinical sequelae based on theavailable data.

HuAB1 treatment induced a dose-dependent reduction of nonclassical CD16⁺monocytes as a PD marker for HuAB1 treatment. The relationship betweenHuAB1 serum concentration and reduction of nonclassical CD16⁺ monocyteswas analyzed and found to be concentration-dependent based on the datacollected 72 hours post-treatment until the end of the study. At ≥5μg/mL HuAB1 in serum, maximum reduction of nonclassical CD16⁺ monocyteswas noted. Therefore, the dose to achieve trough serum concentration at≥5 μg/mL in majority of patients is expected to be the target dose formaximum reduction of nonclassical CD16⁺ monocytes. The optimal exposurerequired to achieve clinical efficacy remains to be explored in clinicaltrials using HuAB1 in patients.

In summary, HuAB1 exhibited nonlinear clearance in the dose rangetested. The PK characteristics observed in healthy volunteers supportdosing of HuAB1 once every 2 weeks or less frequently to maintaindesired drug exposure.

1.7.3.1.3 Clinical Safety Summary of HuAB1

The total number of subjects that received HuAB1 was 36 for both Part 1and Part 2 with 6 subjects in each dose cohort. Dose escalationdecisions were based on the incidence of DLTs plus attributed AEs beyondthe DLT period.

HuAB1 was well tolerated in healthy volunteers up to 3 mg/kg multipledoses. The most common HuAB1 treatment-related toxicities were pruritus,eyelid edema along with facial swelling, fatigue, and headache. Theevents were Grade 1 or 2, and self-limited. The AE profile is similar towhat has been reported in other compounds targeting the CSF1R pathway(Cassier, 2014). At 10 mg/kg, all 6 active subjects experienced moderate(Grade 2) eyelid edema or facial swelling, some accompanied withswelling in hands and feet, blurry vision, and weight increase. Theevents lasted up to 3 months and coincided with prolonged HuAB1 exposureat this dose level.

HuAB1 has shown elevation of liver enzymes, peaking at 2-8 weeksfollowing drug administration and returning to normalization 12 weeksafter discontinuation of drug. Dose-dependent elevations of CK up to 6.8times the upper limit of normal (ULN) and LDH up to 3.2 times ULN werenoted at 1 mg/kg and above; AST elevations up to 2.4 times ULN occurredat 3 mg/kg and above and occurred in a greater percentage of healthyvolunteers with increasing dose; and mild ALT elevation up to 1.2 timesULN occurred at 10 mg/kg in 1 subject. These elevations were consideredto be due more to the mechanism of action of HuAB1-mediated inhibitionof Kupffer cells, rather than any organic failure or injury and were notconsidered clinically significant. HuAB1 was initially tested in healthyvolunteers at a dose of 1 mg/kg and 3 mg/kg body weight. At 1 mg/kg, 7subjects received a single dose and 5 subjects received 2 doses at 14day intervals and were followed up through the 28 day DLT window. In the3 mg/kg healthy volunteer group, 10 subjects received a single dose and2 subjects received 2 doses 14 days apart and were followed up for DLTs.Only 1 subject in the 3 mg/kg cohort had a Grade 1 concurrent increaseof alkaline phosphatase and AST.

1.7.3.2 Nivolumab 1.7.3.2.1 Clinical Pharmacology Summary of Nivolumab

Single-dose PK of nivolumab was evaluated in patients with multipletumor types in CA209001, whereas multiple-dose PK is being evaluated inpatients in CA209003. In addition, a preliminary populationpharmacokinetic (PPK) model has been developed with data from 350patients from CA209001, CA209002, and CA209003.

The PK of nivolumab was studied in patients over a dose range of 0.1 to20 mg/kg administered as a single dose or as multiple doses every 2 or 3weeks. Based on a PPK analysis using data from 909 patients, theclearance (CL) (CV %) is 9.5 mL/h (49.7%), geometric mean volume ofdistribution at steady state (Vss) is 8.0 L (30.4%), and geometric meanelimination half-life (t_(1/2)) is 26.7 days (101%). Steady-stateconcentrations of nivolumab were reached by 12 weeks when administeredat 3 mg/kg every 2 weeks, and systemic accumulation was approximately3-fold. The exposure to nivolumab increased dose proportionally over thedose range of 0.1 to 10 mg/kg administered every 2 weeks (Opdivo PackageInsert, 2015).

Based on a population PK analysis using data from 909 patients, theclearance of nivolumab increased with increasing body weight supportinga weight-based dose. The population PK analysis suggested that thefollowing factors had no clinically important effect on the clearance ofnivolumab: age (29 to 87 years), gender, race, baseline LDH, PD-L1expression, tumor type, tumor size, renal impairment, and mild hepaticimpairment (Opdivo Package Insert, 2015).

1.7.3.2.2 Safety Summary of Nivolumab

Overall, the safety profile of nivolumab monotherapy as well ascombination therapy is manageable and generally consistent acrosscompleted and ongoing clinical trials with no MTD reached at any dosetested up to 10 mg/kg. There was no pattern in the incidence, severity,or causality of AEs to the nivolumab dose level. Most AEs were low-grade(Grade 1 to 2) with relatively few related high-grade (Grade 3 to 4)AEs. Most high-grade events were manageable with the use ofcorticosteroids or hormone replacement therapy (endocrinopathies) asinstructed in the management algorithms provided in the nivolumab IB(Nivolumab IB, 2014).

A total of 39 and 306 patients with selected recurrent ortreatment-refractory malignancies have been treated in a completed Phase1 single-dose study (CA209001) and an ongoing Phase 1 multi-dose study(CA209003), respectively. As the safety profile from CA209003 to date isconsistent with that observed for CA209001, only data from the largerand more recent study, CA209003, are presented below.

In CA209003 (n=306, including 129 patients with NSCLC), as of the 5 Mar.2013 database lock, drug-related AEs of any grade occurred in 75% ofpatients. The most frequent drug-related AEs occurring in at least 5% ofpatients included fatigue (28%), rash (15%), diarrhea (13%), pruritus(11%), nausea (9%), decreased appetite (9%), decreased hemoglobin (6%),and pyrexia (6%). The majority of events were low grade, with Grade 3/4drug-related AEs observed in 17% of patients. The most common Grade 3/4drug-related AEs occurring in at least 1% of patients were fatigue (2%),pneumonitis (1%), diarrhea (1%), abdominal pain (1%), hypophosphatemia(1%), and lymphopenia (1%). Drug-related SAEs occurred in 14% ofpatients; 8% were Grade 3/4 including pneumonitis (1%) and diarrhea(1%). The spectrum, frequency, and severity of drug-related AEs weregenerally similar across the dose levels tested. A review of the safetydata by tumor type (RCC, NSCLC, metastatic castration-resistant prostatecancer [mCRPC], colorectal cancer [CRC], and melanoma) also did not showany clinically meaningful differences in the proportion of patients withAEs noted across tumor type.

Select AEs with potential immune-related causality, previously termed“immune-related adverse events” or “adverse events of special interest”were also analyzed taking into account multiple events, with ratesadjusted for treatment duration. Most events occurred within the first 6months of therapy; cumulative or novel toxicities were not observed withprolonged drug exposure. Nineteen of 306 patients (6%) experienced Grade3/4 treatment-related select AEs. Fifty-two of 230 patients (23%) withdrug-related AEs required management with systemic glucocorticoidsand/or other immunosuppressive agents. Twenty-one of 52 (40%) resumednivolumab therapy after toxicity resolved, while the others discontinuedtherapy.

Although tumor progression was the most common cause of mortality, therewere 3 drug-related deaths associated with Grade 3/4 pneumonitis.Pneumonitis (any grade) occurred in 12 of 306 patients (4%), and Grade3/4 pneumonitis occurred in 4 patients (1%), with clinical presentationsranging from asymptomatic radiographic abnormalities to progressive,diffuse pulmonary infiltrates associated with cough, fever, and/ordyspnea. No clear relationship between the occurrence of pneumonitis andtumor type, dose level, or treatment duration was noted. In 9 of 12patients, pneumonitis was reversible after treatment discontinuationand/or with immunosuppressive therapy (glucocorticoids, infliximab,mycophenolate).

Additional details on the safety profile of nivolumab, including resultsfrom other clinical studies, are also available in the IB and packageinsert (Nivolumab IB, 2014; Opdivo Package Insert, 2015).

1.8 Overall Risk/Benefit Assessment

A number of drug candidates that target the CSF1R pathway are beingstudied in the clinic. These include antibodies that block agonistligand binding to CSF1R or inhibit CSF1R dimerization as well as smallmolecules that block the kinase activity of CSF1R. The safety, PK, andPD of PD-0360324, an antibody to CSF1, in healthy volunteers has beenreported (Sadis, 2009). The most significant treatment-emergent findings(increased liver enzyme levels) and AEs (i.e., periorbital edema)exhibited with PD-0360324 treatment are consistent with the dataobtained to date with HuAB1.

A clinical study of RG7155 (an anti-dimerization CSF1R antibody)included patients with diffuse-type giant cell tumors (Dt-GCT). Allseven evaluable patients showed partial metabolic response in FDG-PETimaging (according to the European Organization for Research andTreatment of Cancer), with two patients approaching a complete metabolicresponse. Five of the seven patients went on to achieve partialresponses at the first assessment. As with other agents targeting theCSF1R pathway, periorbital edema was the most common AE (Ries, 2014).

CSF1 is a major survival factor for TAMs and targeting CSF1R throughHuAB1 should reduce TAM-mediated immunosuppression, resulting instrengthening the anti-tumor response to immunotherapy. Inhibition ofCSF1R by HuAB1 could limit the influence of TAMs on the tumormicroenvironment and be complementary to, and augment current cancertherapies.

Nivolumab has demonstrated clinical activity across several tumor types,particularly melanoma and NSCLC, where it has already been granted FDAapproval. Nivolumab has also demonstrated a manageable safety profile.The most common AEs included fatigue, rash, pruritus, diarrhea, andnausea.

Preliminary reports of specific CSF1R inhibitors suggest that HuAB1 maybe a beneficial treatment for patients with solid tumor malignancies.The robust clinical activity demonstrated by nivolumab in patients withadvanced melanoma, NSCLC and RCC in combination with a manageable safetyprofile supports the further development of this treatment in patientswith advanced cancers.

Based on available clinical safety data, toxicities for HuAB1 andnivolumab do not overlap (with the notable exception of liver enzymeelevations, discussed below) and therefore, cumulative toxicities arenot expected as a result of this combination. HuAB1 has been linked toperiorbital edema, and there has been only one case of peripheral edemawith nivolumab. Additionally, nivolumab has been linked toimmune-related AEs, and there have been no immune-related AEs with HuAB1to date.

There is a temporary increase in liver enzymes (CK, AST, ALT, and LDH)in patients taking HuAB1 due to a reduction of Kupffer cells, and thishas not been associated with any histopathological evidence of liver,cardiac, or skeletal tissue damage. Nivolumab is known to cause hepatictoxicities at a low frequency. Because of the potential for thecombination of HuAB1 and nivolumab to yield elevated liver enzymes withdifferent underlying mechanisms, risk mitigation guidelines have beendesigned to rapidly detect, and appropriately respond to, any evidenceof liver perturbation during this study (Appendix E).

There remains an unmet medical need for cancer patients. Given therobust nonclinical and clinical data supporting these two molecules, thenon-redundant, immune-based mechanisms of actions, and current body ofsafety data from multiple clinical studies, the logical combination ofthese two drugs may be beneficial for patients with cancer who are inneed of expanded therapeutic options.

2 Investigational Plan

2.1 Study Design and Duration

This study is a Phase 1a and 1b, open-label, multicenter, doseescalation and dose expansion study to evaluate the safety,tolerability, PK, and PD of HuAB1 as monotherapy and in combination withnivolumab in patients with selected advanced cancers. HuAB1 is ahumanized monoclonal antibody directed against CSF1R and nivolumab is afully human monoclonal antibody directed against PD-1. For thecombination arms of the study, HuAB1 and nivolumab will be given on Day1 of each 14-day treatment cycle; nivolumab will be given as an IVinfusion over 30 minutes first, with a 30-minute rest between 2infusions, followed by a 30-minute HuAB1 IV infusion.

The study will include a Phase 1a dose escalation and a Phase 1b doseexpansion. Phase 1a consists of two HuAB1 monotherapy reference cohorts(1aM1 and 1aM2) and three dose-escalation cohorts of HuAB1 incombination with nivolumab (1aC1, 1aC2, and 1aC3). Phase 1b consists ofeight cohorts (1b1 through 1b8) across six cancer types. Patients willbe enrolled into either Phase 1aM, 1aC, or Phase 1b of the study, butnot two or all three. The study schematic is shown in FIG. 6.

The study will consist of 3 periods including screening (up to 28 days),treatment, and follow-up/survival follow-up.

2.1.1 Screening Period

All screening evaluations must be completed and reviewed by theInvestigator following the Study Reference Manual for the enrollmentprocess to confirm that patients meet all eligibility criteria beforethe first infusion of study drug. Written informed consent forparticipation in the study must be obtained before performing any studyspecific screening tests or procedures, which are not consideredstandard of care. Screening assessments will be performed within 28 daysprior to the first dose of study drug unless otherwise specified.

Study procedure-related AEs that occur after signing of the ICF andbefore administration of the first study drug dose will be collectedduring this period.

2.1.2 Treatment Period

2.1.2.1 Phase 1a Monotherapy Cohorts (1aM1 and 1aM2) and CombinationDose Escalation Cohorts (1aC1, 1aC2, and 1aC3)

Phase 1a consists of two HuAB1 monotherapy reference cohorts and threedose-escalation cohorts of HuAB1 in combination with nivolumab withminimum of 3 patients enrolled in each cohort. The planned dose levelsand schedules for the Phase 1a cohorts are as follows:

Cohort 1aM1: 2 mg/kg HuAB1, q2w

Cohort 1aM2: 4 mg/kg HuAB1, q2w

Cohort 1aC1: 1 mg/kg HuAB1+3 mg/kg nivolumab, q2w

Cohort 1aC2: 2 mg/kg HuAB1+3 mg/kg nivolumab, q2w

Cohort 1aC3: 4 mg/kg HuAB1+3 mg/kg nivolumab, q2w

The 2 mg/kg HuAB1 monotherapy cohort (1aM1) and the 1 mg/kgHuAB1+nivolumab combination cohort (1aC1) will be initiated first inparallel with sequential enrollment order, following a 3+3 design,starting with the 1aM1 monotherapy cohort. Patients in these cohortswill be treated for a total of two 14-day treatment cycles within the28-day DLT period.

The 4 mg/kg HuAB1 monotherapy cohort (1aM2) will open after the DLTperiod is cleared in the 2 mg/kg HuAB1 monotherapy cohort (1aM1); the 2mg/kg HuAB1/nivolumab combination cohort will only start after the DLTperiods are cleared in both the 1aC1 HuAB1/nivolumab combination and1aM1 HuAB1 monotherapy cohorts. The 4 mg/kg HuAB1/nivolumab combinationcohort (1aC3) will open only after the DLT periods are cleared in the1aC2 HuAB1/nivolumab combination and 1aM2 HuAB1 monotherapy cohorts.Depending on the outcome of the 4 mg/kg HuAB1 monotherapy cohort, higheror a lower intermedian dose cohorts for both monotherapy and combinationtherapy (e.g., 3 mg/kg HuAB1 alone or in combination with nivolumab) maybe opened up per the decision of Cohort Review Committee. All doseescalation decisions will be based on assessment of DLTs, overallsafety, and tolerability. Dose escalation decisions will be agreed uponbetween the Investigators and the Sponsor. Prior to initiating each newdose level or expanding an existing dose level, a safety teleconferencewill be held wherein the Investigator(s) and Sponsor will review patientdata, including, but not limited to, demographics, drug dosing,concomitant medications, hematology and serum chemistry, and AEs; andconfer and document agreement that dose escalation or expanding anexisting dose level is considered appropriate. If the Investigator(s)and Sponsor collectively agree, following review of safety, PK, and PDdata, that a different dose escalation scheme (e.g., an intermediateHuAB1 dose of 3 mg/kg alone or in combination with nivolumab) should beused than the one outlined, this will be permitted. Review of safety,PK, and PD parameters may inform decisions to add cohorts withalternative dose levels or dose regimens (e.g., less frequent dosing) inorder to reach an optimal target exposure.

DLT evaluation and enrollment decisions will follow the guidance in theTable 2 below:

TABLE 2 Algorithm for Phase la dose escalation decisions Number ofPatients with DLT at a Given Dose Level Dose Escalation Decision Rule0/3 Escalation will occur into the next highest dose cohort 1/3 Enrollthree more patients in same cohort ≥2/3  Stop enrollment. Enter threemore patients at the lower dose level, if only three were previouslyentered 1/6 Open next cohort ≥2/6  Stop enrollment. Enter three morepatients at the lower dose level, if only three were previously entered

Dose escalation will continue in the monothereapy and combinationtreatment arms until either the MTD or maximum planned dose of HuAB1 isreached, with a minimum of 3 patients enrolled in each cohort.

The MTD is defined as the highest dose associated with DLTs in less than33% of patients (less than 2 out of 6 patients) receiving HuAB1 orHuAB1+nivolumab combination therapy, administered during the 28-day DLTperiod. This will normally be the dose recommended for further study;however, based on review of safety, PK, and PD data, the RD could belower than the MTD. If the MTD is not reached, and the highest evaluatedHuAB1 dose alone or in combination with nivolumab is well tolerated, thedata will be reviewed to assess whether further dose escalations up to 6mg/kg HuAB1 are warranted.

If the MTD is not reached during the Phase 1a combination doseescalation, or subsequent cycles of treatment in cleared Phase 1acombination cohorts provide additional insight on the safety profile, anRD may be selected based on overall tolerability, safety, PK, and PD.

If a patient in Phase 1aC does not receive 2 doses of each study drugand does not complete the safety assessment (e.g., safety lab and/or AEreporting) in the 28-day DLT period for reasons other than drug-relatedAEs (e.g., disease progression or withdrawal of consent), then anadditional patient will be enrolled into the cohort so that the cohorthas at least three patients evaluable for the DLT period. All suchdiscussions and decisions will be documented as part of the doseescalation decision-making process.

Upon completion of the 28-day DLT period, Phase 1a patients mayparticipate in an Extended Treatment Period following the guidelines inSection 4.1.2.2.

2.1.2.1.1 Dose Limiting Toxicity

A DLT is defined as a study drug-related ≥Grade 3 AE (using NationalCancer Institute [NCI] Common Terminology Criteria for Adverse Events[CTCAE] v4.03) occurring during the first 28-day DLT period, excluding:Grade 3 tumor flare (defined as local pain, irritation, or rashlocalized at sites of known or suspected tumor), Grade 3 rash, Grade 3immune-related adverse event (irAE, defined below) that resolved to aGrade 1 or less within 28 days, or a transient (resolving within 6 hoursof onset) Grade 3 infusion-related AE. An irAE is defined as aclinically significant AE that is associated with study drug exposure,of unknown etiology, and is consistent with an immune-mediatedmechanism.

2.1.2.2 Phase 1a Extended Treatment Period

Upon completion of the DLT period, patients from the Phase 1aM and 1aCcohorts may participate in an Extended Treatment Period, which begins onDay 1 of Cycle 3 (Study Day 29).

Patients from the Phase 1aM cohorts are allowed to continue to receiveHuAB1 monotherapy at the same HuAB1 dose level and patients from thePhase 1aC cohorts are allowed to continue to receive HuAB1 incombination with nivolumab at the same dose levels until diseaseprogression, unacceptable toxicity, or other reason for treatmentdiscontinuation.

2.1.2.3 Phase 1b Expansion Cohorts

To further characterize safety and efficacy of HuAB1 in combination withnivolumab, Phase 1b will enroll up to 8 expansion cohorts in 6 advancedcancer types. Enrollment in Phase 1b will begin when an RD has beenidentified by the Cohort Review Committee based on overall safety,tolerability, PK, and PD data.

2.1.3 Follow-Up Period

Patients who discontinue treatment while showing clinical benefit(complete response [CR], partial response [PR], or stable disease [SD])for reasons other than disease progression should have follow-up fortumor assessments and any study drug-related AEs as specified below. Thefollow-up period begins at the Treatment Completion/Early Terminationvisit.

Follow-up visits include the following (refer to Section 6 for the fullschedule):

Tumor assessments will continue every 12 (±2) weeks.

Review of study drug-related AEs, until these AEs resolve, return tobaseline or are stabilized per treating Investigator's assessment. AllAEs will be documented for a minimum of 100 days after the last dose ORuntil any one of the above conditions is met.

During the follow-up period, if the patient undergoes local therapy(e.g., resection, radiation) or a new systemic therapy is initiated, thepatient should be followed for survival every 3 months (Section 4.1.4).

2.1.4 Survival Follow-Up

A patient who agrees to survival follow-up after withdrawal from studytreatment, discontinues from study drug treatment due to progression ofdisease, or discontinues follow-up visits described in Section 4.1.3will be followed every 3 months for survival, or more frequently asneeded. Follow-up for survival may be conducted by telephone, ratherthan a required in-person visit.

2.1.5 Study Duration

Patients who receive study drug(s) may continue as long as theyexperience clinical benefit in the opinion of the investigator or untilunacceptable toxicity or symptomatic deterioration attributed to diseaseprogression as determined by the investigator after an integratedassessment of radiographic data, biopsy results (if available), andclinical status, or withdrawal of consent.

2.1.6 Stopping Rules 2.1.6.1 Stopping Rules for Phase 1a

If 2 or more patients in any dose level experience a DLT within the28-day DLT evaluation period, the Investigators and Sponsor will reviewthe data and follow the guidelines in Table 2 (Section 4.1.2.1). If doseescalation is terminated due to DLTs, then the evaluated dose below thatwhich the stopping rule was invoked will be declared the MTD.

2.1.6.2 Stopping Rules for all Cohorts

Management of drug-related Grade 4 or 5 toxicities will follow theAdverse Event Management Tables (Appendix E and F).

The Sponsor will discuss such cases with the Cohort Review Committee andthe study Investigators as appropriate to determine further enrollment.IRBs will be notified by the Investigators of all cases and decisionsregarding continued enrollment.

2.1.6.3 Stopping Rules for Clinical Deterioration

Accumulating clinical evidence indicates that the emergence of objectiveresponses to agents that activate anti-tumor immune responses may followdelayed kinetics of weeks or months, and can be preceded by initialapparent progression of disease with the appearance of new lesions orsome enlarging of lesions while certain index lesions are regressing(“mixed response”). It is thus reasonable to allow patients experiencingapparent progression to continue to receive treatment until progressionis confirmed at the next imaging assessment (Section 5.3.8). Theseconsiderations should be balanced by clinical judgment as to whether thepatient is clinically deteriorating and unlikely to receive any benefitfrom continued treatment.

Such deterioration will be assessed to have occurred after a clinicalevent that, in the Investigator's opinion, is attributable to diseaseprogression and is unlikely to reverse with continued study treatmentand therefore indicates that the patient is not benefiting from studytreatment and cannot be managed by the addition of supportive care. Thedecision to stop treatment should be discussed with the Sponsor'sMedical Monitor or designee. Examples of events that may, in theInvestigator's opinion, indicate a lack of clinical benefit include, butare not limited to, the following:

Eastern Cooperative Oncology Group (ECOG) score increase of at least 2points from baseline (e.g. from 0 to 2).

Habitual changes such as changes in activities and symptoms includingreduction in appetite and/or sleep, altered awareness, and increasedpain-related symptoms due to cancer.

Progression of disease confirmed by the treating Investigator.

Any setting where the initiation of new anti-neoplastic therapy has beendeemed beneficial to the patient even in the absence of any suchdocumented clinical events.

2.2 Study Population

2.2.1 Planned Number of Patients and Study Centers

The total number of patients planned for this study is estimated to be270; approximately 30 patients in Part 1a and 240 patients in Part 1b(approximately 30 patients for each of the eight Phase 1b cohorts).There will be 65 to 70 study centers participating in this study. Duringenrollment of any expansion cohort, if the observed number of responsesmakes it unlikely to achieve a target response rate for that indication(e.g., 10%), then further recruitment to that cohort may be suspended orterminated.

2.2.2 Inclusion Criteria for all Cohorts

For entry into the study, ALL of the following criteria must be met.

-   -   1. Measurable disease by Computed tomography (CT)/magnetic        resonance imaging (MRI) as per Response Evaluation Criteria in        Solid Tumors (RECIST) v1.1 and preferably performed within 28        days of first dose.    -   2. Patients must have at least 1 tumor site that can be biopsied        and are willing to recommended pre-treatment, on-treatment, and        post-progression biopsies (except for patients in the        Glioblastoma cohort); post-progression biopsy is optional for        patients in Phase 1b cohorts. Biopsies will be performed        according to treating institution's own guidelines from minimum        of 10 patients in each Phase 1b cohort.    -   3. Archival formalin-fixed paraffin-embedded (FFPE) tumor        material, if available    -   4. Understand and sign an IRB/IEC-approved ICF prior to any        study-specific evaluation    -   5. Age ≥18 years    -   6. ECOG performance status of 0 or 1    -   7. Willing and able to comply with all study procedures    -   8. Prior focal radiotherapy must be completed at least 2 weeks        before first dose of study drug administration. No        radiopharmaceuticals (strontium, samarium) within 8 weeks before        study drug administration.    -   9. Prior surgery that requires general anesthesia must be        completed at least 2 weeks before study drug administration.        Surgery requiring local/epidural anesthesia must be completed at        least 72 hours before study drug administration and patients        should be recovered.    -   10. Screening laboratory values must meet the following        criteria:

Hematological

-   -   a. White blood cells (WBCs) ≥2000 cells/μL    -   b. Neutrophils ≥1500 cells/μL    -   c. Platelets ≥100×10³/μL    -   d. Hemoglobin ≥9.0 g/dL        -   Serum creatinine ≤1.5×ULN or creatinine clearance of ≥40            mL/minute (using Cockcroft/Gault Formula)

${{Female}\mspace{14mu} {CrCl}} = \frac{\left( {140 - {{age}\mspace{14mu} {in}\mspace{14mu} {years}}} \right) \times \left( {{weight}\mspace{14mu} {in}\mspace{14mu} {kg}} \right) \times 0.85}{72 \times \left( {{serum}\mspace{14mu} {creatinine}\mspace{14mu} {in}\mspace{14mu} {mg}\text{/}{dL}} \right)}$${{Male}\mspace{14mu} {CrCl}} = \frac{\left( {140 - {{age}\mspace{14mu} {in}\mspace{14mu} {years}}} \right) \times \left( {{weight}\mspace{14mu} {in}\mspace{14mu} {kg}} \right)}{72 \times \left( {{serum}\mspace{14mu} {creatinine}\mspace{14mu} {in}\mspace{14mu} {mg}\text{/}{dL}} \right)}$

-   -   e. PT/INR≤1.5×ULN and PTT (aPTT)≤1.5×ULN

Hepatic

-   -   a. AST or ALT ≤3×ULN without, and ≤5×ULN with hepatic metastasis    -   b. Bilirubin ≤1.5×ULN (except patients with Gilbert's syndrome,        who must have total bilirubin <3 mg/dL)    -   11. Women of childbearing potential (WOCBP) must have a negative        serum β-human chorionic gonadotropin (β-hCG) at Screening and        agree to use a reliable form of contraception (e.g., oral        contraceptives, intrauterine device or double barrier method of        condom and spermicidal) for at least 28 days prior to the first        dose of any study drug during the Treatment Period (and        Treatment/Follow-up if receiving study drug), and for at least        23 weeks after the last dose of any study drug. Specific country        requirements will be followed (e.g., in the United Kingdom,        women of childbearing potential and male patients and their        partners of childbearing potential must use two methods of        contraception, one of which must be a barrier method, for the        duration of the study).    -   12. Men who are sexually active with WOCBP must agree to follow        instructions for method(s) of contraception for the duration of        treatment with study drug plus 31 weeks post-treatment        completion.

2.2.3 Exclusion Criteria of all Cohorts

Patients who meet ANY of the following criteria will be excluded fromstudy entry.

-   -   1. Current or history of clinically significant muscle disorders        (e.g., myositis), recent unresolved muscle injury, or any        condition known to elevate serum CK levels    -   2. Immunosuppressive doses of systemic medications, such as        steroids or absorbed topical steroids (doses >10 mg/day        prednisone or equivalent daily) must be discontinued at least 2        weeks before study drug administration except in the case of        tumor-related AE treatment. Patients with a condition requiring        chronic systemic treatment with either corticosteroids (inhaled        or topical steroids and adrenal replacement steroid doses >10        mg/day prednisone equivalent) or other immunosuppressive        medications within 2 weeks of treatment are permitted in the        absence of active autoimmune disease.    -   3. Decreased cardiac function with NYHA >Class 2    -   4. Uncontrolled or significant heart disorder such as unstable        angina    -   5. Significant abnormalities on ECG at screening. QTcF >450 msec        for males or >470 msec for females at screening    -   6. History of anti-drug antibodies, severe allergic,        anaphylactic, or other infusion-related reaction to a previous        biologic agent    -   7. Known history of sensitivity to Tween 20 (polysorbate 20) and        polysorbate 80 containing infusions    -   8. Consumption of non-pasteurized milk on a regular basis, or        known significant risk of exposure to opportunistic        intracellular infections such as listeria or other such        pathogens    -   9. Non-oncology vaccine therapies for prevention of infectious        diseases (e.g., HPV vaccine) within 4 weeks of study drug        administration. The inactivated seasonal influenza vaccine can        be given to subjects before treatment and while on therapy        without restriction. Influenza vaccines containing live virus or        other clinically indicated vaccinations for infectious diseases        (i.e., pneumovax, varicella, etc.) may be permitted; but must be        discussed with the Sponsor's Medical Monitor and may require a        study drug washout period prior to and after administration of        vaccine.    -   10. Current unresolved infection or history of chronic, active,        clinically significant infection (viral, bacterial, fungal, or        other) which, in the opinion of the Investigator, would preclude        the patient from exposure to a biologic agent, or pose a risk to        patient safety    -   11. Positive test for latent tuberculosis (TB) at Screening        (Quantiferon test) or evidence of active TB    -   12. Lack of peripheral venous access or any condition that would        interfere with drug administration or collection of study        samples    -   13. Any uncontrolled medical condition or psychiatric disorder        which, in the opinion of the Investigator, would pose a risk to        patient safety or interfere with study participation or        interpretation of individual patient results    -   14. Concomitant use of statins while on study. However, a        patient using statins for over 3 months prior to study drug        administration and in stable status without CK rise may be        permitted to enroll    -   15. Pregnant or breastfeeding    -   16. Active, known or suspected autoimmune disease. Patients with        type I diabetes mellitus, hypothyroidism requiring only hormone        replacement, skin disorders (such as vitiligo, psoriasis, or        alopecia) not requiring systemic treatment, or conditions not        expected to recur in the absence of an external trigger are        permitted to enroll.    -   17. Participation in a another investigational drug trial within        28 days prior to first dose of study drug administration, or        while on this study    -   18. Known history of testing positive for human immunodeficiency        virus (HIV) 1&2 or known acquired immunodeficiency syndrome        (AIDS)    -   19. Positive test for hepatitis B virus surface antigen (HBsAg)        or detectable hepatitis C virus ribonucleic acid (HCV RNA)        indicating acute or chronic infection    -   20. Symptomatic interstitial lung disease or inflammatory        pneumonitis    -   21. Untreated or active central nervous system (CNS) or        leptomeningeal metastases. Patients are eligible if metastases        have been treated and patients are neurologically returned to        baseline (except for residual signs or symptoms related to the        CNS treatment) for at least 2 weeks prior to first dose of study        drug administration    -   22. Evidence of hepatic cirrhosis, confirmed by alkaline        phosphatase elevations and concomitantly elevated ALT/AST ratio        and hypoalbuminemia (<3.0 g/dL)    -   23. Evidence of coagulopathy or bleeding diathesis    -   24. Any uncontrolled inflammatory GI disease including Crohn's        Disease and ulcerative colitis.    -   25. Prior exposure to any CSF1R pathway inhibitors    -   26. Transfusion completed within 72 hours prior to first dose of        study drug administration

2.2.4 Additional Inclusion and Exclusion Criteria for Selected Cohorts2.2.4.1 Phase 1a 2.2.4.1.1 HuAB1 Monotherapy Cohorts

Inclusion:

-   -   1. Histologically or cytologically confirmed solid tumor that is        locally recurrent or metastatic and has progressed following        standard treatment or is not appropriate for standard treatment

2.2.4.1.2 HuAB1+Nivolumab Combination Cohorts

Inclusion:

-   -   1. Histologically or cytologically confirmed solid tumor that is        locally recurrent or metastatic and has progressed following        standard treatment or is not appropriate for standard treatment

Exclusion

-   -   1. Prior exposure to any PD-1 pathway targeting drug

2.2.4.2 Phase 1b 2.2.4.2.1 Cohort 1b1: NSCLC, (Anti-PD-1 Therapy Naïve,Second or Third Lines)

Inclusion:

-   -   1. Patients with histologically or cytologically documented        squamous or non-squamous NSCLC who present with Stage IIIB or IV        disease (according to version 7 of the international association        for the Study of Lung Cancer Staging manual in Thoracic        oncology) and with recurrent or progressive disease following        multi-modal therapy (radiation therapy, surgical resection or        definitive chemoradiation) for locally advanced or metastatic        disease    -   2. Disease progression or recurrence during/after a platinum        doublet-based chemotherapy regimen for advanced or metastatic        disease.        -   Maintenance therapy following platinum doublet-based            chemotherapy is not considered a separate therapy regimen.        -   Subjects who received platinum-containing adjuvant,            neoadjuvant or definitive chemoradiation therapy given for            locally advanced disease, and developed recurrent (local or            metastatic) disease within 6 months of completing therapy            are eligible.        -   Subjects with recurrent disease >6 months after            platinum-containing adjuvant, neoadjuvant or definitive            chemo-radiation therapy given for locally advanced disease,            who also subsequently progressed during or after a platinum            doublet-based regimen given to treat the recurrence, are            eligible.

Exclusion:

-   -   1. Prior exposure to any PD-1 pathway targeting drug

2.2.4.2.2 Cohort 1b2: NSCLC (Refractory on Anti-PD-1 Targeting Drugs)

Inclusion

-   -   1. Patients with histologically or cytologically documented        NSCLC who present with Stage IIIB locally advanced or Stage IV        disease.    -   2. Patient has radiological evidence of disease progression        during treatment with a PD-1 pathway targeting drug that did not        produce a clinical response (i.e., neither CR nor PR) and with        progressive disease as the best response.    -   3. To be considered refractory, patients should have had no        clinical response after receiving at least 2 doses of any PD-1        targeting drug

Exclusion

-   -   1. Intolerance to any PD-1 pathway targeting drug.        -   Intolerance is defined as any treatment-related Grade 4 AE,            or any treatment-related Grade 2 or 3 AE that is            unacceptable to the patient and persists despite standard            countermeasures.

2.2.4.2.3 Cohort 1b3 Melanoma (Anti-PD-1 Therapy Naïve)

Inclusion

-   -   1. Patients with histologically or cytologically documented        Stage III or IV melanoma as per the American Joint Committee on        Cancer (AJCC) staging system who are either refractory to,        intolerant to, or have refused, standard therapy for treatment        of metastatic melanoma.    -   2. Objective evidence of disease progression (clinical or        radiological) during or after at least 1 BRAF inhibitor (if BRAF        V600 mutation positive)    -   3. Known BRAF wild-type as per regionally acceptable V600        mutational status testing

Exclusion

-   -   1. Prior therapy with any PD-1 pathway targeting drug.    -   2. BRAF mutant subjects and those with indeterminate or unknown        BRAF status are not permitted to participate in this study

2.2.4.2.4 Cohort 1b4: Melanoma (Refractory or Relapsed on Anti-PD-1Targeting Drug)

Inclusion:

-   -   1. Patients with histologically or cytologically documented        unresectable Stage III or IV melanoma as per the AJCC staging        system    -   2. Patient has radiological evidence of disease progression        during treatment with a Checkpoint inhibitor or PD-1 targeting        drug that did not produce a clinical benefit (no CR, PR, or SD)        and progressive disease as the best response or disease        progression after the initial clinical benefit of either CR, PR        or SD while receiving treatment with a PD-1 targeting drug    -   3. To be considered refractory, patients should have had no        response after receiving at least 2 doses of any PD-1 targeting        drug    -   4. Objective evidence of disease progression (clinical or        radiological) during or after at least 1 BRAF inhibitor (if BRAF        V600 mutation positive)    -   5. Prior anticancer therapy including dacarbazine, BRAF        inhibitor (if BRAF V600 mutation positive) and/or ipilimumab and        palliative radiotherapy must have been completed at least 3        weeks prior to study drug administration    -   6. No prior treatment with PD-1 targeting drug within 6 weeks        prior to first dose of study drug

Exclusion:

-   -   1. BRAF mutant subjects and those with indeterminate or unknown        BRAF status are not permitted to participate in this study    -   2. Ocular melanoma.    -   3. Prior intolerance to any PD-1 targeting drug        -   Intolerance is defined as any treatment-related Grade 4 AE,            or any treatment-related Grade 2 or 3 AE that is            unacceptable to the patient and persists despite standard            countermeasures. The reason for intolerance should be fully            documented.

2.2.4.2.5 Cohort 1b5: Squamous Cell Carcinoma of the Head and Neck(SCCHN) (Second Line)

Inclusion:

-   -   1. Patients with histologically or cytologically documented        recurrent or metastatic SCCHN (oral cavity, pharynx, larynx),        stage III or IV and not amenable to local therapy with curative        intent (surgery or radiation therapy with or without        chemotherapy)    -   2. Tumor progression or recurrence within 6 months of the last        dose of platinum therapy in the adjuvant (i.e. with radiation        after surgery), primary (i.e., with radiation), recurrent, or        metastatic setting. Clinical progression after platinum therapy        is an allowable event for entry and is defined as progression of        a lesion at least 10 mm in size that is amenable to caliper        measurement (e.g., superficial skin lesion as per RECIST v1.1)        or a lesion that has been visualized and photographically        recorded with measurements and shown to have progressed.

Exclusion:

-   -   1. Histologically confirmed recurrent or metastatic carcinoma of        the nasopharynx and any salivary gland or non-squamous histology    -   2. Prior exposure to any PD-1 pathway targeting drug

2.2.4.2.6 Cohort 1b6: Pancreatic Cancer (Second Line)

Inclusion:

-   -   1. Histologically or cytologically documented localized or        metastatic adenocarcinoma of the pancreas, which has failed (or        are not indicated for) standard therapy    -   2. Patients who may have received prior surgery, radiation        therapy for the management of locally advanced or metastatic        adenocarcinoma of the pancreas providing that disease        progression has been documented. All toxicities should be        resolved, and the last fraction of radiation treatment was        completed at least 4 weeks prior to first study drug        administration

Exclusion:

-   -   1. Patients with islet cell neoplasms, neuroendocrine or other        primary tumors in the pancreas    -   2. Patients with active pancreatitis    -   3. Prior exposure to any PD-1 pathway targeting drug    -   4. Ascites of Grade 2 or higher

2.2.4.2.7 Cohort 1b7: Colorectal Cancer (Third Line)

Inclusion:

-   -   1. Histologically or cytologically documented adenocarcinoma of        colon or rectum    -   2. Metastatic CRC with documented disease progression after the        last administration of standard therapies or intolerance to        standard therapies (and approved therapies had to include a        fluoropyrimidine, oxaliplatin, irinotecan, bevacizumab, and, if        KRAS wild-type, cetuximab or panitumumab).

Exclusion:

-   -   1. Prior exposure to any PD-1 pathway targeting drug

2.2.4.2.8 Cohort 1b8: Malignant Glioma (First Recurrence)

Inclusion:

-   -   1. Histologically or cytologically documented advanced World        Health Organization (WHO) Grade IV malignant glioma        (glioblastoma or gliosarcoma)    -   2. Previous treatment with surgery, radiotherapy and        temozolomide    -   3. Documented first recurrence of GBM by diagnostic biopsy or        contrast-enhanced MRI performed within 21 days of first study        drug administration per Response Assessment in Neuro-oncology        (RANO) criteria    -   4. If on steroids, dose must be stable or decreased for a        minimum of 5 days prior to baseline MRI

Exclusion:

-   -   1. Prior treatment with bevacizumab or another VEGF- or        VEGFR-targeting agent    -   2. Recent evidence of more than Grade 1 CNS hemorrhage on        baseline MRI scan    -   3. History or evidence upon physiological/neurological exam of        CNS disease (e.g., seizures) unrelated to cancer unless        adequately controlled by medication or potentially interfering        with the study treatment    -   4. Patients unable to have a head contrast-enhanced MRI due to a        pre-existing medical condition including a pacemaker or        implantable cardioverter defibrillator (ICD) device    -   5. More than 1 recurrence of glioblastoma or gliosarcoma    -   6. Prior exposure to any PD-1 pathway targeting drug

2.3 Concomitant Medications

All medications taken within 28 days before the administration of thefirst dose of any study drug and all concomitant therapy administeredduring the study until 100 days after last dose of any study drug willbe recorded.

Information on all prior treatments indicated for advanced cancer,including chemotherapy, biochemotherapy, immunotherapy, radiation,surgery, biologic, and experimental therapy will be collected.

No concomitant medication information will be collected followingpatient discontinuation from the study except for concomitant medicationuse associated with study drug-related AEs or AEs that lead todiscontinuation from the study.

2.3.1 Prohibited and/or Restricted Treatments

The following medications are prohibited during the study (unlessutilized to treat a drug-related AE or specified in the eligibilitysection):

Immunosuppressive Agents

Immunosuppressive doses of systemic corticosteroids. Inhaled or topicalsteroids, and adrenal replacement steroid doses >10 mg daily prednisoneequivalent, are permitted in the absence of active autoimmune disease.Steroids are also permitted to treat tumor-related AEs as clinicallyindicated.

Vaccines Except as Noted in Section 4.3.2

Statins for treatment of hypercholesterolemia. Statins will be allowedonly if the patient is on a stable dose for over 3 months prior to thestudy and is in stable status without any CK elevations

Other therapies including biologic, immunotherapy, extensivenon-palliative radiation therapy, standard treatments, orinvestigational agents or devices

2.3.2 Permitted Therapy

Patients are permitted to use of topical, ocular, intra-articular,intranasal, and inhaled corticosteroids (with minimal systemicabsorption). Adrenal replacement steroid doses >10 mg daily prednisoneare permitted. A brief (less than 3 weeks) course of corticosteroids forprophylaxis (e.g., contrast dye allergy) or for treatment ofnon-autoimmune conditions (e.g., delayed-type hypersensitivity reactioncaused by a contact allergen) and also for the treatment oftumor-related AE is permitted.

Concomitant palliative and supportive care for disease-related symptoms(including bisphosphonates and RANK-L inhibitors) is allowed ifinitiated prior to first dose of study drug administration. Transfusionsare permitted as needed.

The inactivated seasonal influenza vaccine can be given to subjectswhile on therapy without restriction. Influenza vaccines containing livevirus or other clinically indicated vaccinations for infectious diseases(i.e., pneumovax, varicella, etc.) may be permitted; but must bediscussed with the Sponsor's Medical Monitor and may require a studydrug washout period prior to and after administration of the vaccine.

Concomitant use of statins will be allowed only if the patient is on astable dose for over 3 months prior to the study and is in stable statuswithout any CK elevations.

No routine premedication will be administered for initial HuAB1 andnivolumab doses. If a patient develops nausea, vomiting, or otherinfusion-related AEs, the patient may be pre-medicated withanti-emetics, steroids, or antihistamines prior to subsequent infusionsof study drugs at the discretion of the Investigator. The treatment willbe administered according to the institution's standard practice, andshould be captured on the patient's CRF.

2.4 Discontinuation of Patients Following any Treatment with Study Drug

Patients MUST discontinue study drugs for any of the following reasons:

Withdrawal of informed consent (patient's decision to withdraw for anyreason)

Any clinical significant AE, abnormal laboratory test results orintercurrent illness which, in the opinion of the Investigator,indicates that continued participation in the study is not in the bestinterest of the patient

Patients who are required to have prohibited concomitant medications

Pregnancy

Termination of the study by the Sponsor

Loss of ability to freely provide consent through imprisonment orinvoluntary incarceration for treatment of either a psychiatric orphysical (e.g., infectious disease) illness

Documented disease progression or clinical deterioration while receivingactive study therapy

Non-compliance by the patient

All patients who discontinue study treatment should comply with protocolspecified follow-up procedures as outlined in Section 6. The onlyexception to this requirement is when a patient withdraws consent forall study procedures or loses the ability to consent freely (i.e., isimprisoned or involuntarily incarcerated for the treatment of either apsychiatric or physical illness).

If a patient was withdrawn before completing the study, the reason forwithdrawal must be entered on the appropriate CRF. The date and reasonfor cessation of HuAB1 and/or nivolumab will be documented, and theInvestigator must make every effort to perform the TreatmentCompletion/Early Termination visit procedures. Patients will be followedfor 100 days after the last dose of HuAB1 for safety and those withongoing SAEs will be followed until either resolution or stabilization.

2.5 Post-Treatment Follow up

Patients who discontinue treatment while still receiving clinicalbenefit (i.e., CR, PR or SD) should get follow-up tumor scansper-protocol to determine the duration of response, unless consent iswithdrawn.

3 Study Drugs

In this study, both the study drugs, HuAB1 and nivolumab, are consideredInvestigational [Medicinal] Products (IP/IMP). The product descriptionsfor HuAB1 and nivolumab are described in Table 3 and Table 4:

TABLE 3 Study Drug for Phase 1a Monotherapy Cohorts Product Description/Storage Conditions Class and Dosage Form Potency IP Open LabelPackaging/Appearance (per label) HuAB1 Solution for 100 mg (20 mg/mL) 5mL per vial X vials per Sterile, aqueous, 2-8° C. (36-46° F.). Injectioncarton/open-label colorless, pyrogen-free Protect from freezing solutionin 5 mL Type 1 glass vials fitted with butyl rubber stoppers and flip-upaluminum seals

TABLE 4 Study Drugs for Phase 1a Combination Dose Escalation and Phase1b Dose Expansion Cohorts Product Description/ Storage Conditions Classand Dosage Form Potency IP Open Label Packaging/Appearance (per label)Nivolumab Solution for 100 mg (10 mg/mL) 10 mL per vial 10 vials percarton/ Clear to opalescent 2-8° C. Protect from Injection Open-labelcolorless to pale yellow light and freezing liquid. May containparticles HuAB1 Solution for 100 mg (20 mg/mL) 5 mL per vial X vials perSterile, aqueous, 2-8° C. (36-46° F.). Injection carton/open-labelcolorless, pyrogen-free Protect from freezing solution in 10 mL Type 1glass vials fitted with butyl rubber stoppers and flip-up aluminum seals

3.1 Investigational Products

An investigational product, also known as investigational medicinalproduct in some regions, is defined as a pharmaceutical form of anactive substance or placebo being tested or used as a reference in aclinical study, including products already with a marketingauthorization but used or assembled (formulated or packaged) differentlythan the authorized form, or used for an unauthorized indication, orwhen used to gain further information about the authorized form. In thisprotocol, the investigational products are HuAB1 and nivolumab.

3.2 Study Drug Dosing and Dose Modification

3.2.1 Dosing

For the combination therapy, nivolumab should always be administeredfirst as a 30-minute IV infusion, with a 30-minute rest between 2infusions, followed by HuAB1 30-minute infusion. Patients may be dosedno less than 12 days from the previous dose.

For the 4 mg/kg monotherapy cohort (1aM2) and combination doseescalation cohorts 1aC2 and 1aC3, the dose interval between the firstand second patients in each cohort should be at least 24 hours forsafety monitoring.

Dosing calculations should be based on the body weight assessed at Cycle1 Day 1 prior to the first dose of study drug administration. It is notnecessary to re-calculate subsequent doses if the patient's weight iswithin 10% of the weight used to calculate the previous dose. All dosesshould be rounded to the nearest milligram.

Patients should be carefully monitored for infusion reactions duringstudy drug administration. If an acute infusion reaction is noted,patients should be managed according to the guidelines in Section 5.3.10and Appendix E and F.

Doses of study drugs may be interrupted, delayed, or discontinueddepending on how well the patient tolerates the treatment.

All vials are for single use only. Further instructions on study drugpreparation and administration will be provided in the Pharmacy Manual.

3.2.1.1 Nivolumab Dosing

Patients in combination therapy cohorts will receive the nivolumabinfusion first at a dose of 3 mg/kg as a 30-minute IV infusion, on Day 1of each 14-day treatment cycle.

There will be no dose escalations or reductions of nivolumab allowed.Patients may be dosed no less than 12 days from the previous dose. Thereare no pre-medications recommended for nivolumab on the first cycle.Refer to the nivolumab IB for preparation and handling instructions.

3.2.1.2 HuAB1 Dosing

For patients in the combination therapy cohorts, the HuAB1 infusion willbe administered 30 minutes after the end of the nivolumab infusion as a30-minute IV infusion, on Day 1 of each 14-day treatment cycle. Forpatients in the monotherapy cohorts, the HuAB1 infusion can be initiatedat any time as a 30-minute IV infusion on Day 1 of each 14-day treatmentcycle.

HuAB1 dosing may be modified based on toxicities noted during thetreatment period. If necessary, the dose will be adjusted based on thetoxicity-modification table (Appendices E and F).

A research pharmacist (or other responsible personnel) will prepare thesolution for administration. After calculating the number of vials,based on the patient's weight, the study drug product will be dilutedwith 0.9% Sodium Chloride Injection, USP. Prepared HuAB1 should beadministered within 6 hours after preparation (ambient temperature). TheIV administration setup for HuAB1 infusion must contain a 0.22 μmin-line filter or a 0.22 μm syringe filter. HuAB1 will be administeredunder medical supervision as a 30 minute (±5 minutes) IV infusion via aperipheral vein or central venous catheter. No incompatibilities betweenHuAB1 infusion and polyvinyl chloride (PVC), ethylene/propylene IVcomponents, or glass bottles have been observed.

3.2.2 Dose Delay for HuAB1 and Nivolumab

Administration of HuAB1 in monotherapy or HuAB1/nivolumab in combinationtherapy should be delayed for the following:

Any Grade 3 fatigue which does not resolve to Grade 1 or baseline beforethe next treatment visit

Any Grade 2 or 3 drug-related laboratory abnormalities would not requirea dose delay unless clinically indicated or specified in the protocol orAdverse Event Management table. Please discuss with the Sponsor'sMedical Monitor or designee as needed.

For dose delays or modifications for all other AEs please refer to theAE Management tables in Appendix E.

Patients who require a dose delay of HuAB1 or HuAB1+nivolumab should bere-evaluated weekly or more frequently if clinically indicated andresume study drug dosing when re-treatment criteria are met.

If a patient experiences an infusion reaction to HuAB1, or nivolumab, orboth study drugs, the infusion reaction should be treated following theinfusion reaction treatment guidelines in Section 5.3.10 and Appendix Eand F.

3.2.3 Criteria to Resume Treatment with HuAB1 and Nivolumab

Patients may resume treatment with HuAB1 or HuAB1+nivolumab when thedrug-related AE(s) resolve(s) to Grade 1 or baseline as noted in the AEmanagement tables in Appendices E and F.

3.2.4 Dose Reduction with HuAB1

Dose reductions for HuAB1 may be permitted for patients on prolongedtreatment beyond the DLT period in Phase 1a or any patient in Phase 1bper the guidelines in the appropriate AE management tables in AppendicesE and F. If dose reductions or interruptions that do not fall withinthese guidelines are being considered by the Investigator, these willrequire discussion with and approval by the Sponsor, or designee.

3.2.5 Dose Discontinuation Criteria for HuAB1 and Nivolumab

Treatment of HuAB1 in monotherapy or HuAB1 in combination with nivolumabshould be permanently discontinued for the following:

Any Grade 2 drug-related uveitis, eye pain or blurred vision that doesnot respond to topical therapy and does not improve to Grade 1 withinthe second re-treatment period OR that requires systemic treatment

Any Grade 3 or higher infusion related reactions and hypersensitivityrequiring discontinuation and re-initiation of therapy will requireconsultation with the Sponsor's Medical Monitor or designee.

Any Grade 3 non-skin, drug-related AE lasting >7 days, includingdrug-related uveitis, pneumonitis, hypoxia, bronchospasm, andendocrinopathies with the following exceptions:

Grade 3 drug-related endocrinopathies adequately controlled with onlyphysiologic hormone replacement do not require discontinuation

Grade 3 drug-related laboratory abnormalities do not require treatmentdiscontinuation except:

Grade 3 drug-related thrombocytopenia >7 days or associated with Grade≥2 bleeding requires discontinuation

Any drug-related liver function test (LFT) abnormality that meets thefollowing criteria requires discontinuation:

AST or ALT 10×ULN

Total bilirubin >3×ULN (>5×ULN with concurrent liver metastases)

AST or ALT >3×ULN AND total bilirubin >2×ULN, in the absence of aconcurrent increase of alkaline phosphatase

Any Grade 4 drug-related AE or laboratory abnormality, except for thefollowing events which do not require discontinuation:

Grade 4 neutropenia □ 7 days

Grade 4 lymphopenia or leukopenia □ 7 days

Isolated Grade 4 amylase or lipase abnormalities that are not associatedwith symptoms or clinical manifestations of pancreatitis. The Sponsor'sMedical Monitor should be consulted for Grade 4 amylase or lipaseabnormalities.

Isolated Grade 4 electrolyte imbalances/abnormalities that are notassociated with clinical sequelae and are corrected withsupplementation/appropriate management within 72 hours of their onset

Grade 4 drug-related endocrinopathy AEs, such as adrenal insufficiency,adrenocorticotropic hormone (ACTH) deficiency, hyper- or hypothyroidism,or glucose intolerance, which resolve or are adequately controlled withphysiologic hormone replacement (corticosteroids, thyroid hormones) orglucose-controlling agents, respectively, may not requirediscontinuation after discussion with and approval from the Sponsor'sMedical Monitor.

Any event that leads to delay in dosing lasting >6 weeks from theprevious dose requires discontinuation, with the following exceptions:

Dosing delays to allow for prolonged steroid tapers to managedrug-related adverse events are allowed. Prior to re-initiatingtreatment in a patient with a dosing delay lasting >6 weeks from theprevious dose, the Sponsor's Medical Monitor must be consulted. Tumorassessments should continue as per-protocol even if dosing is delayed.Periodic study visits to assess safety and laboratory studies shouldalso continue per protocol, or more frequently if clinically indicatedduring such dosing delays or per the Investigator's discretion

Dosing delays lasting >6 weeks from the previous dose that occur fornon-drug-related reasons may be allowed if approved by the Sponsor'sMedical Monitor. Prior to re-initiating treatment in a patient with adosing delay lasting >6 weeks, the Sponsor's Medical Monitor must beconsulted. Tumor assessments should continue per protocol every 8 weekseven if dosing is delayed. Periodic study visits to assess safety andlaboratory studies should also continue per-protocol or more frequentlyif clinically indicated during such dosing delays or per theInvestigator's discretion.

Any AE, laboratory abnormality, or intercurrent illness which, in thejudgment of the Investigator, presents a substantial clinical risk tothe patient with continued HuAB1 and/or nivolumab dosing

Any Grade 3 or higher neurological toxicity

Any Grade 3 or higher periorbital edema and persistent Grade 2periorbital edema requiring 2 missed doses unless approved by Sponsor'sMedical Monitor

Any Grade 3 or higher drug-related diarrhea or colitis interfering withactivities of daily living.

Any Grade 3 or 4 skin toxicity

Any Grade 3 or higher uveitis

If the causality of the adverse event requiring discontinuation isconfirmed to be due to one of the study drugs in the combinationtherapy, the other drug may be continued per protocol schedule under thefollowing scenarios:

Timely resolution of the adverse event based on the treatmentmodification table

Clinical benefit is shown by the subject based on Investigatorassessment

3.2.6 Infusion Delays and Missed Doses with HuAB1 and Nivolumab

In the case that an infusion cannot be administered at a scheduledvisit, it must be administered as soon as possible. If the delay isbetween 1 and 3 days, the procedures at the original scheduled visitshould be performed. If the delay is more than 3 days, the procedures atthe next visit should be performed, and subsequent visits will be resetto follow a 2-week dosing interval (the infusion at the originalscheduled visit will be considered a missed dose). The time between twotreatment cycles should be no less than 12 days.

Patients may miss up to 2 consecutive doses (up to 6 weeks betweendoses) and may resume the study drug if the event returns to baseline or≤Grade 1 within 6 weeks of treatment interruption. Omission ofadditional dosing longer than 6 weeks for AEs will necessitate thepatient's discontinuation from the study unless allowed by the Sponsor.Patients may miss doses in the course of participation in the study,including missed doses for scheduled vacations or other personal reasonsas needed, but not more than 2 doses sequentially unless approved by theSponsor's Medical Monitor.

3.2.7 Intra-Patient Dose Escalation with HuAB1 and Nivolumab

Intra-patient dose escalation is not allowed for nivolumab or HuAB1.

3.2.8 Treatment Beyond Disease Progression with HuAB1 and Nivolumab

Accumulating evidence indicates a minority of patients treated withimmunotherapy may derive clinical benefit despite initial evidence ofprogressive disease (Wolchok, 2009)

Patients treated with HuAB1 and nivolumab will be permitted to continueHuAB1 and nivolumab treatment beyond initial RECIST v1.1 definedprogressive disease, assessed by the Investigator, as long as thefollowing criteria are met:

Patients who will be treated beyond disease progression must review andsign an ICF before continuing on study drug

Investigator-assessed clinical benefit, and do not have rapid diseaseprogression

Tolerance of study drugs

Stable performance status

Treatment beyond progression will not delay an imminent intervention toprevent serious complications of disease progression (e.g., CNSmetastases)

A radiographic assessment/scan should be performed approximately 8 weeksafter initial Investigator-assessed progression to determine whetherthere has been a decrease in the tumor size or continued progressivedisease. The assessment of clinical benefit should be balanced byclinical judgment as to whether the patient is clinically deterioratingand unlikely to receive any benefit from continued treatment with HuAB1and nivolumab.

If the Investigator feels that the HuAB1 and nivolumab patient continuesto achieve clinical benefit by continuing treatment, the patient shouldremain on the trial and continue to receive monitoring according to thetime and event schedules per protocol.

For the patients who continue nivolumab study therapy beyondprogression, further progression is defined as an additional 10%increase in tumor burden from time of initial progression. This includesan increase in the sum of diameters of all target lesions and/or thediameters of new measurable lesions compared to the time of initialprogression. HuAB1 and nivolumab treatment should be discontinuedpermanently upon documentation of further progression.

Assessment for new lesions will follow guidelines in RECIST v1.1(Appendix G).

3.2.9 Dose Modification Algorithms for Immuno-Oncology Agents

Immuno-oncology agents are associated with AEs that can differ inseverity and duration compared to AEs caused by other therapeuticclasses. HuAB1 and nivolumab are considered immuno-oncology agents inthis protocol. Early recognition and management of AEs associated withimmuno-oncology agents may mitigate severe toxicity. Managementalgorithms have been developed to assist Investigators in assessing andmanaging the following classes of AEs:

Gastrointestinal

Renal

Pulmonary

Hepatic

Endocrinopathy

Skin

Neurological

Infusion reaction

Periorbital edema

Uveitis

3.2.10 Treatment of HuAB1 and Nivolumab Related Infusion Reactions

HuAB1 and nivolumab may induce infusion or hypersensitivity reactions.If such a reaction were to occur, it may manifest with fever, chills,rigors, headache, rash, pruritus, arthralgia, hypo- or hypertension,bronchospasm, or other symptoms.

Infusion reactions should be graded according to CTCAE v4.03 guidelines.Any Grade 3 or 4 infusion reaction should be reported within 24 hours tothe study Medical Monitor and reported as an SAE if it meets thecriteria.

The nivolumab infusion will be administered first, with a 30-minute restbetween the 2 infusions, followed by HuAB1 30-minute infusion. It may beunclear if an infusion reaction is due to HuAB1, nivolumab, or to bothstudy drugs. Therefore, one set of treatment recommendations (based onthe most conservative treatments for infusion reactions due to eitherstudy drug) is provided below and may be modified based on clinicaljudgment, local treatment standards and guidelines, and/or specificsymptoms, as appropriate:

For Grade 1 Symptoms: (Mild Reaction [e.g., Localized CutaneousReactions Including Mild Pruritus, Flushing, Rash], Requires InfusionRate to be Decreased; Intervention May be Indicated.)

Decrease the rate of the study drug infusion until recovery fromsymptoms.

Remain at bedside and monitor the patient's vital signs until resolutionof symptoms. Diphenhydramine 50 mg may be administered at the discretionof the treating physician.

When symptoms resolve, restart the infusion at the original infusionrate.

If a patient has an infusion reaction with nivolumab, HuAB1 can be given(without prophylactic medications) if the infusion reaction resolveswithin 3 hours. For scheduling purposes, HuAB1 infusion may be given thenext day. Prophylactic pre-infusion medications should be given prior toall subsequent nivolumab infusions.

If a patient has an infusion reaction with HuAB1, prophylacticpre-infusion medications should be given prior to all subsequent HuAB1and nivolumab infusions.

The following prophylactic pre-infusion medications are recommendedprior to future infusions of HuAB1 and nivolumab: diphenhydramine 50 mg(or equivalent) and/or paracetamol (acetaminophen) 325 to 1000 mg atleast 30 minutes before additional study drug administrations.

For Grade 2 Symptoms: (Moderate Reaction [i.e., any Symptom not ListedAbove (Mild Symptoms) or Below (Severe Symptoms) Such as GeneralizedPruritus, Flushing, Rash, Dyspnea, Hypotension with Systolic BloodPressure >80 mmHg], Requires Infusion Interruption but Responds Promptlyto Symptomatic Treatment [e.g., Antihistamines, NonsteroidalAnti-Inflammatory Drugs, Narcotics, Corticosteroids, IV Fluids];Prophylactic Pre-Infusion Medications Indicated for ≤24 Hours.)

Interrupt the study drug infusion.

Begin an IV infusion of normal saline, and treat the patient withdiphenhydramine 50 mg IV (or equivalent) and/or paracetamol(acetaminophen) 325 to 1000 mg.

Remain at bedside and monitor the patient's vital signs until resolutionof symptoms. Corticosteroid therapy may be administered at thediscretion of the treating physician.

When symptoms resolve, restart the infusion at 50% of the originalinfusion rate; if no further complications ensue after 30 minutes, therate may be increased to 100% of the original infusion rate.

Monitor the patient closely. If symptoms recur, immediately discontinuethe infusion; no further study drug will be administered at that visit.Administer diphenhydramine 50 mg IV, and remain at bedside and monitorthe patient until resolution of symptoms.

If a patient has an infusion reaction with nivolumab infusion, HuAB1infusion can be given (without prophylactic medications) if the infusionreaction resolves within 3 hours. For scheduling purposes, the HuAB1infusion may be given the next day. Prophylactic pre-infusionmedications should be given prior to all subsequent nivolumab infusions.

If a patient has an infusion reaction with HuAB1, prophylacticpre-infusion medications should be given prior to all subsequent HuAB1and nivolumab infusions.

The following prophylactic pre-infusion medications are recommendedprior to future infusions of HuAB1 and nivolumab: diphenhydramine 50 mg(or equivalent) and/or paracetamol (acetaminophen) 325 to 1000 mg shouldbe administered at least 30 minutes before additional study drugadministrations. If necessary, corticosteroids (up to 25 mg ofSoluCortef or equivalent) may be used.

The amount of study drug infused must be recorded.

For Grade 3 or Grade 4 Symptoms: (Severe Reaction Such as Bronchospasm,Generalized Urticaria, Systolic Blood Pressure <80 mmHg, or Angioedema;Grade 3 Symptoms Including Prolonged Symptom, which Requires 6 or MoreHours to Respond to Symptomatic Medication and/or Discontinuation ofInfusion; Recurrence of Symptoms Following Initial Improvement;Hospitalization Indicated for Other Clinical Sequelae, Such as RenalImpairment, Pulmonary Infiltrates; Grade 4: Life-Threatening; Pressor orVentilation Support Indicated.)

Immediately discontinue the study drug infusion. No further study drugwill be administered. The amount of study drug infused must be recordedon the CRF.

Begin an IV infusion of normal saline, and treat the patient as follows:Recommend bronchodilators, epinephrine 0.2 to 1.0 mg of a 1:1,000solution for subcutaneous administration or 0.1 to 0.25 mg of a 1:10,000solution injected slowly for IV administration, and/or diphenhydramine50 mg IV with methylprednisolone 100 mg IV (or equivalent), as needed.

Remain at bedside and monitor the patient's vital signs until recoveryfrom symptoms.

The patient should be monitored until the Investigator is comfortablethat the symptoms will not recur.

Investigators should follow their institutional guidelines for thetreatment of anaphylaxis.

In the case of late-occurring hypersensitivity symptoms (e.g.,appearance of a localized or generalized pruritus within 1 week aftertreatment), symptomatic treatment may be given (e.g., oralantihistamine, or corticosteroids).

3.3 Method of Assigning Patient Identification

Patients must be able to provide written informed consent and meet alleligibility criteria. No waivers of inclusion or exclusion criteria willbe granted by Sponsor or its designee for any patient enrolled in thestudy. Before enrolling a patient, all eligibility criteria must besatisfied.

Patients who qualify for Phase 1a of the study will be enrolled asfollows:

Three patients in the Phase 1aM1 monotherapy cohort will be enrolledfirst to be treated with 2 mg/kg HuAB1 every 14 days during the 28-dayDLT period.

Once the above monotherapy cohort is fully enrolled, a cohort (1aC1) of3 new patients will be enrolled to be treated with 1 mg/kg HuAB1 incombination with 3 mg/kg nivolumab every 14 days during the 28-day DLTperiod.

Dose escalation into the 4 mg/kg HuAB1 monotherapy cohort (1aM2) willproceed once the DLT period is cleared in the 2 mg/kg HuAB1 monotherapycohort (1aM1).

Dose escalation into increasing dose levels of HuAB1 in combination withnivolumab will proceed until DLTs are observed either in the HuAB1monotherapy or the HuAB1 in combination with nivolumab cohorts afterdiscussion and agreement between the participating Investigators andSponsor's Medical Monitor.

In Phase 1b, approximately 30 patients will be enrolled per cohort.Enrollment will be open for all cohorts in parallel and will continueuntil the enrollment target is reached. Once a cohort is filled, furtherenrollment will be restricted to the cohort(s) that have not beenfilled. A total of approximately 240 patients will be enrolled in thePhase 1b arm of the study.

The Investigator may repeat qualifying lab tests and vitals/ECGs priorto enrollment if a non-qualifying finding is considered an error or anacute finding is likely to meet eligibility criteria upon repeattesting.

3.4 Blinding/Unblinding

This is an open-label study and there will be no blinding or unblindingof patients during this study.

4 Study Assessments and Procedures 4.1 Schedule of Assessments

The schedule of assessment tables are attached to the protocol asAppendices A, B, and C.

4.2 Study Procedures by Visit 4.2.1 Phase 1a Monotherapy 4.2.1.1Screening Period (Day −28 to Day 0)

Patients who have fully consented to participation in the study willundergo Screening assessments within 28 days (4 weeks) prior toadministration of the first infusion of HuAB1 (unless otherwise stated).To determine if the patient meets all inclusion criteria and does notviolate any exclusion criteria, the following procedures will beperformed (Appendix A):

Written, signed informed consent must be collected prior to anystudy-specific procedures

Complete medical and disease history

Demographic and baseline characteristics

Complete physical examination, including height and weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest)

ECOG performance status evaluation

Screening labs (as described in Appendix A, footnote g)

Clinical safety labs (as described in Appendix A, footnote h)

12-lead ECG (required at Screening, and if clinically indicated duringthe study)

Radiological imaging: CT/MRI is to be performed within 28 days prior tothe first infusion of HuAB1. If the MRI is performed as part of thepatient's standard of care within 28 days of the first study infusion itdoes not need to be repeated if the documentation of results is providedand is adequate for an assessment.

Serum pregnancy test (β-hCG), for women of childbearing potential

Biopsy collection (for analyses described in Appendix D)

SAE reporting, if applicable

Document prior and concurrent medications

4.2.1.2 Cycle 1, Day 1

The following procedures will be performed:

Prior to HuAB1 infusion (within 72 hours unless otherwise stated):

Verification of eligibility

Update medical and disease history to capture any changes from Screening

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate and temperature insupine position after 5 minutes rest)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix A, footnote h); resultsmust be reviewed before dosing)

Serum β-hCG (evaluated by local laboratories) will be performed prior tothe first dose of HuAB1 only on women of childbearing potential

Blood collection for:

Serum (for analyses described in Appendix D, excluding nivolumabanalyses)

Whole blood (for analyses described in Appendix D)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 by IV infusion over 30 minutes

Post HuAB1 administration:

Post-dose vital signs (heart rate, blood pressure, and temperature insupine position after 5 minutes rest) at the following time points aftercompletion of the IV infusion:

5 MINUTES, 15 MINUTES, 30 MINUTES, AND 1 HOUR

15 minutes (±5 minutes) post-dose:

Blood collection for serum (for HuAB1 PK)

4 hours (±60 minutes) post-dose:

Blood collection for serum (for HuAB1 PK)

4.2.1.3 Cycle 1, Day 2

Study patients will return to the study center on Day 2 for 24-hour (±6hours) post-dose assessments. No treatment will be administered duringthis visit, but the following assessments will be completed:

Blood collection for:

Serum (for HuAB1 PK and cytokine multiplex panel)

Whole blood (for gene expression analysis)

AE reporting, if applicable

Review of concomitant medications

4.2.1.4 Cycle 1, Day 4

Study patients will return to the study center on Day 4 for 72-hour (±12hours) post-dose assessments. No treatment will be administered duringthis visit, but the following assessments will be completed:

Blood collection

Serum (for HuAB1 PK)

Whole blood (for CD14⁺/CD16⁺ monocyte and gene expression analyses)

AE reporting, if applicable

Review of concomitant medications

4.2.1.5 Cycle 1, Day 8

Study patients will return to the study center on Day 8 for 168-hour(±24 hours) post-dose assessments. No treatment will be administeredduring this visit, but the following assessments will be completed:

Physical examination

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest)

Clinical safety labs (as described in Appendix A, footnote h)

Blood collection for:

Serum (for HuAB1 PK and cytokine multiplex panel)

Whole blood (for CD14⁺/CD16⁺ monocyte and gene expression analyses)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

4.2.1.6 Cycle 2, Day 1

The following procedures will be performed:

Prior to HuAB1 infusion (within 72 hours unless otherwise stated):

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix A, footnote h; resultsmust be reviewed before dosing:

Blood collection for:

Serum (for analyses described in Appendix D, excluding nivolumabanalyses)

Whole blood (for analyses described in Appendix D, except the MDSCpanel)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 by IV infusion over 30 minutes

Post HuAB1 administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 minutes, 15 minutes, 30 minutes, and 1 hour

15 minutes (±5 minutes) post-dose:

Blood collection for serum (for HuAB1 PK)

4.2.1.7 End of Cycle 2

For Phase 1a patients in monotherapy cohort, if at the end of Cycle 2,the Investigator determines that the patient may benefit from continueddosing with HuAB1, entry into the Extended Treatment Period may beoffered.

If the patient is continuing onto the Extended Treatment Period (Cycle 3and beyond), proceed to procedures outlined in Section 6.2.1.8.

If the patient does not qualify to receive further doses of HuAB1, thepatient will return to the clinic for the Treatment Completion/EarlyTermination visit outlined in Section 6.2.1.9.

4.2.1.8 Extended Treatment—Cycle 3 and Subsequent Cycles, Day 1

Phase 1a extended treatment for patients in monotherapy cohort may beginon Cycle 3, Day 1 (Study Day 29). Dosing will be discontinued if thepatient experiences either disease progression or unacceptable toxicity.

At each infusion visit, patients are to remain at the study site aftereach administration of HuAB1 until completion of all post-doseassessments for safety monitoring. The following assessments will beperformed at each visit unless otherwise noted (Appendix A):

Prior to each infusion of study drug (within 72 hours unless otherwisestated):

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix A, footnote h; resultsmust be reviewed before dosing)

Radiological imaging: CT/MRI scan performed every 8 weeks for the first12 months for patients who remain on treatment (and every 12 weeksthereafter) and 28 days (±7 days) after the last dose of studytreatment.

Biopsy collection (prior to Cycle 3 only; for analyses described inAppendix D)

Blood collection for:

Serum (for analyses described in Appendix D) with the followingexceptions:

HuAB1 PK for Cycles 3, 5, 9, 13, and 21

HuAB1 ADA for Cycles 3, 5, 13, and 21

ANA for Cycles 3, 5, 9, 13, 21, then every 6 cycles while on treatment

CSF1 and IL34 for Cycle 3 and 9

Cytokine multiplex panel for Cycles 3, 9, and 21

Whole blood (for analyses described in Appendix D) with the followingexceptions:

CD14⁺/CD16⁺ monocytes for Cycle 3, and 9

MDSC panel for Cycle 3 only

Gene expression analysis for Cycle 3, 5, 9, 13, and 21

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 by IV infusion over 30 minutes

Post HuAB1 administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 MINUTES, 15 MINUTES, 30 MINUTES, AND 1 HOUR

15 minutes (±5 minutes) post-dose:

Blood collection for serum (for analyses described in Appendix D) withthe following exceptions:

HuAB1 PK for Cycle 8 only

4.2.1.9 Treatment Completion or Early Termination Visit

Patients will return to the study center approximately 28 (±7) daysafter their last infusion of HuAB1.

The following assessments will be performed:

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix A, footnote h)

12-lead ECG

Radiological imaging: CT/MRI scan does not need to be repeated ifperformed within 8 weeks prior to the Treatment Completion/EarlyTermination Visit or if tumor progression was previously determined.

Serum pregnancy test (β-hCG), if applicable

Biopsy for patients who progressed (for analyses described in AppendixD)

Blood collection

Serum (for analyses described in Appendix D, excluding nivolumabanalyses)

Whole blood (for CD14⁺/CD16⁺ monocyte analysis and gene expressionanalysis only)

AE reporting, if applicable

Review of concomitant medications

4.2.2 Phase 1a Combination Dose Escalation 4.2.2.1 Screening Period (Day−28 to Day 0)

Patients who have consented to participation in the study will undergoscreening assessments within 28 days (4 weeks) prior to administrationof the first infusion of HuAB1 and nivolumab (unless otherwise stated).To determine if the patient meets all inclusion criteria and does notviolate any exclusion criteria, the following procedures will beperformed (Appendix B):

Written, signed informed consent must be collected prior to anystudy-specific procedures

Complete medical and disease history

Demographic and baseline characteristics

Complete physical examination, including height and weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Screening labs (as described in Appendix B, footnote g)

Clinical safety labs (as described in Appendix B, footnote h)

12-lead ECG (required at Screening, and if clinically indicated duringthe study)

Radiological imaging: CT/MRI to be performed within 28 days prior toCycle 1 Day 1. If the CT/MRI is performed as part of the patient'sstandard of care within 28 days of Cycle 1 Day 1, it does not need to berepeated if the documentation of results is provided and is adequate forRECIST 1.1

Serum pregnancy test (β-hCG), 5 days prior to Cycle 1, Day 1, for womenof childbearing potential

Biopsy collection (for analyses described in Appendix D)

SAE reporting, if applicable

Document prior and concurrent medications

4.2.2.2 Cycle 1, Day 1

The following procedures will be performed:

Prior to HuAB1 and nivolumab infusion (within 72 hours unless otherwisestated):

Verification of eligibility

Update medical and disease history to capture any changes from Screening

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h; resultsmust be reviewed before dosing)

Serum β-hCG (evaluated by local laboratories) will be performed prior tothe first dose of study drug only on women of childbearing potential

Blood collection for:

Serum (for analyses described in Appendix D)

Whole blood (for analyses described in Appendix D)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 and nivolumab will each be administeredby IV infusion over 30 minutes. Nivolumab will be given first, with a30-minute rest between the 2 infusions, followed by HuAB1 30.

Post HuAB1 and nivolumab administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of each IV infusion:

5 minutes and 15 minutes after nivolumab dose

5 minutes, 15 minutes, 30 minutes, and 1 hour after HuAB1 dose

15 minutes (±5 minutes) post-HuAB1 dose:

Blood collection for serum (for HuAB1 and nivolumab PK analysis)

4 hours (±60 minutes) post-HuAB1 dose:

Blood collection for serum (for HuAB1 PK only)

4.2.2.3 Cycle 1, Day 2

Study patients will return to the study center on Day 2 for 24-hour (±6hours) post-dose assessments. No treatment will be administered duringthis visit, but the following assessments will be completed:

Blood collection for:

Serum (for HuAB1 PK and cytokine multiplex panel)

Whole blood (for gene expression analysis)

AE reporting, if applicable

Review of concomitant medications

4.2.2.4 Cycle 1, Day 4

Study patients will return to the study center on Day 4 for 72 hour (±12hours) post-dose assessments. No treatment will be administered duringthis visit, but the following assessments will be completed:

Blood collection for:

Serum (for PK only)

Whole blood (for CD14⁺/CD16⁺ monocyte and gene expression analyses)

AE reporting, if applicable

Review of concomitant medications

4.2.2.5 Cycle 1, Day 8

Study patients will return to the study center on Day 8 for 168-hour(±24 hours) post-dose assessments. No treatment will be administeredduring this visit, but the following assessments will be completed:

Physical examination

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

Clinical safety labs (as described in Appendix B, footnote h)

Blood collection for:

Serum (for HuAB1 PK and cytokine multiplex panel)

Whole blood (for CD14⁺/CD16⁺ monocyte and gene expression analyses)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

4.2.2.6 Cycle 2, Day 1

The following procedures will be performed:

Prior to HuAB1 and nivolumab infusion (within 72 hours unless otherwisestated):

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h; resultsmust be reviewed before dosing)

Blood collection for:

Serum (for analyses described in Appendix D)

Whole blood (for analyses described in Appendix D, except the MDSCpanel)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 and nivolumab will each be administeredby IV infusion over 30 minutes. Nivolumab will be given first, with a30-minute rest between the 2 infusions, followed by HuAB1.

Post HuAB1 and nivolumab administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 minutes and 15 minutes after nivolumab dose

5 minutes, 15 minutes, 30 minutes, and 1 hour after HuAB1 dose

15 minutes (±5 minutes) post-HuAB1 dose:

Blood collection for serum (for HuAB1 PK only)

4.2.2.7 End of Cycle 2

For Phase 1a patients in the combination cohort, if at the end of Cycle2 the Investigator determines that the patient may benefit fromcontinued dosing with HuAB1 and nivolumab, entry into the ExtendedTreatment Period may be offered.

If the patient is continuing onto the Extended Treatment Period (Cycle 3and beyond), proceed to procedures outlined in Section 6.2.2.8.

If the patient does not qualify to receive further study drug, thepatient will return to the clinic for the Treatment Completion/EarlyTermination visit outlined in Section 6.2.2.9.

4.2.2.8 Extended Treatment—Cycle 3 and Subsequent Cycles, Day 1

Phase 1a extended treatment for patients in combination dose escalationcohorts may begin on Cycle 3, Day 1 (Study Day 29).

At each infusion visit, patients are to remain at the study site aftereach administration of HuAB1 and nivolumab until completion of allpost-dose assessments for safety monitoring. The following assessmentswill be performed at each visit unless otherwise noted (Appendix B):

Prior to each infusion of study drugs (within ≤72 hours unless otherwisestated):

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h; resultsmust be reviewed before dosing)

Radiological imaging: CT/MRI scan performed every 8 weeks for the first12 months for patients who remain on treatment (and every 12 weeksthereafter) and 28 days (±7 days) after the last dose of studytreatment.

Biopsy collection (for analyses described in Appendix D)

Blood collection for:

Serum (for analyses described in Appendix D) with the followingexceptions:

HuAB1 PK for Cycles 3, 5, 9, 13, and 21 only

Nivolumab PK for Cycles 3, 5, 9, 13, and 21 only

HuAB1 and nivolumab ADA for Cycles 3, 5, 13, and 21 only

ANA for Cycles 3, 5, 9, 13, 21, then every 6 cycles while on treatment

CSF1, IL34 for Cycle 3 and 9 only

Cytokine multiplex panel for Cycles 3, 9, and 21 only

Whole blood (for analyses described in Appendix D) with the followingexceptions:

CD14⁺/CD16⁺ for Cycle 3 and 11 only

Myeloid-derived suppressor cell panel for Cycle 3 only

Gene expression analysis for Cycle 3, 5, 9, 13, and 21 only

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 and nivolumab will each be administeredby IV infusion over 30 minutes. Nivolumab will be given first, with a30-minute rest between the 2 infusions, followed by HuAB1.

Post HuAB1 and nivolumab administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 minutes and 15 minutes after nivolumab dose

5 minutes, 15 minutes, 30 minutes, and 1 hour after HuAB1 dose

15 minutes (±5 minutes) post-HuAB1 dose:

Blood collection for serum (for analyses described in Appendix D) withthe following exceptions:

HuAB1 and nivolumab PK for Cycle 8 only

4.2.2.9 Treatment Completion or Early Termination Visit

Patients will return to the study center approximately 28 (±7) daysafter their last infusion of HuAB1 and nivolumab, or in the event apatient discontinues prematurely from the study.

The following assessments will be performed:

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h)

12-lead ECG

Radiological imaging: CT/MRI scan does not need to be repeated ifperformed within 8 weeks prior to the Treatment Completion/EarlyTermination Visit or if tumor progression was previously determined.

Serum pregnancy test (β-hCG), if applicable

Biopsy for patients who progressed (for analyses described in AppendixD)

Blood collection for:

Serum (for analyses described in Appendix D)

Whole blood (for CD14⁺/CD16⁺ monocyte analysis and gene expression byRNA sequencing only)

AE reporting, if applicable

Review of concomitant medications

4.2.3 Phase 1b Combination Dose Expansion 4.2.3.1 Screening Period (Day−28 to Day 0)

Patients who have fully consented to participation in the study willundergo Screening assessments within 28 days (4 weeks) prior toadministration of the first infusion of HuAB1 and nivolumab (unlessotherwise stated). To determine if the patient meets all inclusioncriteria and does not violate any exclusion criteria, the followingprocedures will be performed (Appendix B):

Written, signed informed consent must be collected prior to anystudy-specific procedures

Complete medical and disease history

Demographic and baseline characteristics

Complete physical examination, including height and weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Screening labs (as described in Appendix B, footnote g)

Clinical safety labs (as described in Appendix B, footnote h)

12-lead ECG (required at Screening, and if clinically indicated duringthe study)

Radiological imaging: CT/MRI to be performed within 28 days prior to thefirst infusion of study drug. If the MRI is performed as part of thepatient's standard of care within 28 days of the first study infusion itdoes not need to be repeated if the documentation of results is providedand is adequate for RECIST 1.1.

Serum pregnancy test (β-HCG), 5 days prior to Cycle 1, Day 1, for womenof childbearing potential

Biopsy collection (for analyses described in Appendix D)

SAE reporting, if applicable

Document prior and concurrent medications

4.2.3.2 Cycle 1, Day 1

The following procedures will be performed:

Prior to HuAB1 and nivolumab infusion (within 72 hours unless otherwisestated):

Verification of eligibility

Update medical and disease history to capture any changes from Screening

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h; resultsmust be reviewed before dosing)

Serum β-hCG (evaluated by local laboratories) will be performed prior tothe first dose of study drug only on women of childbearing potential

Blood collection for:

Serum (for analyses described in Appendix D)

Whole blood (for analyses described in Appendix D)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 and nivolumab will each be administeredby IV infusion over 30 minutes. Nivolumab will be given first, with a30-minute rest between the 2 infusions, followed by HuAB1.

Post-HuAB1 and nivolumab administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 minutes and 15 minutes after nivolumab dose

5 minutes, 15 minutes, 30 minutes, and 1 hour after HuAB1 dose

15 minutes (±5 minutes) post-HuAB1 dose:

Blood collection for serum (for HuAB1 and nivolumab PK analysis)

4 hours (±60 minutes) post-HuAB1 dose:

Blood collection for serum (for HuAB1 PK only)

4.2.3.3 Cycle 1, Day 2

Study patients will return to the study center on Day 2 for 24-hour (±6hours) post-dose assessments. No treatment will be administered duringthis visit, but the following assessments will be completed:

Blood collection for:

Serum (for HuAB1 PK and cytokine multiplex panel)

Whole blood (for gene expression analysis)

AE reporting, if applicable

Review of concomitant medications

4.2.3.4 Cycle 1, Day 4

Study patients will return to the study center on Day 4 for 72-hour (±12hours) post-dose assessments. No treatment will be administered duringthis visit, but the following assessments will be completed:

Blood collection for:

Serum (for HuAB1 PK only)

Whole blood (for CD14⁺/CD16⁺ monocyte and gene expression analyses)

AE reporting, if applicable

Review of concomitant medications

4.2.3.5 Cycle 1, Day 8

Study patients will return to the study center on Day 8 for 168-hour(±24 hours) post-dose assessments. No treatment will be administeredduring this visit, but the following assessments will be completed:

Physical examination

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

Clinical safety labs (as described in Appendix B, footnote h)

Blood collection for:

Serum (for HuAB1 PK and cytokine multiplex panel)

Whole blood (for CD14⁺/CD16⁺ monocyte and gene expression analyses)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

4.2.3.6 Cycle 2, Day 1

The following procedures will be performed:

Prior to HuAB1 and nivolumab infusion (within 72 hours unless otherwisestated):

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h; resultsmust be reviewed before dosing)

Blood collection for:

Serum (for analyses described in Appendix D)

Whole blood (for analyses described in Appendix D, except the MDSCpanel)

Frozen PBMC (for T cell phenotype analysis)

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 and nivolumab will each be administeredby IV infusion over 30 minutes. Nivolumab will be given first, with a30-minute rest between the 2 infusions, followed by HuAB1.

Post-HuAB1 and nivolumab administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 minutes and 15 minutes after nivolumab dose

5 minutes, 15 minutes, 30 minutes, and 1 hour after HuAB1 dose

15 minutes (±5 minutes) post-HuAB1 dose:

Blood collection for serum (for HuAB1 PK only)

4.2.3.7 Cycle 3 and Subsequent Cycles, Day 1

At each infusion visit, patients are to remain at the study site aftereach administration of HuAB1 and nivolumab until completion of allpost-dose assessments for safety monitoring. The following assessmentswill be performed at each visit unless otherwise noted (Appendix B):

Prior to each infusion of study drugs (within ≤72 hours unless otherwisestated):

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h; resultsmust be reviewed before dosing)

Radiological imaging: CT/MRI scan performed every 8 weeks for the first12 months for patients who remain on treatment (and every 12 weeksthereafter) and 28 days (±7 days) after the last dose of studytreatment.

Biopsy collection (for analyses described in Appendix D)

Blood collection

Serum (for analyses described in Appendix D) with the followingexceptions:

HuAB1 PK for Cycles 3, 5, 9, 13, and 21 only

Nivolumab PK for Cycles 3, 5, 9, 13, and 21 only

HuAB1 and nivolumab ADA for Cycles 3, 5, 13, and 21 only

ANA for Cycles 3, 5, 9, 13, 21, then every 6 cycles while on treatment

CSF1, IL34 for Cycle 3 and 9 only

Cytokine multiplex panel for Cycles 3, 9, and 21 only

Whole blood (for analyses described in Appendix D) with the followingexceptions:

CD14⁺/CD16⁺ for Cycle 3 and 9 only

MDSC panel for Cycle 3 only

Gene expression analysis for Cycle 3, 5, 9, 13, and 21 only

AE reporting, if applicable

Review of concomitant medications

Study drug administration: HuAB1 and nivolumab will each be administeredby IV infusion over 30 minutes. Nivolumab will be given first, with a30-minute rest between the 2 infusions, followed by HuAB1.

Post-HuAB1 and nivolumab administration:

Post-dose vital signs (blood pressure, pulse, respiratory rate, andtemperature in supine position after 5 minutes rest) at the followingtime points after completion of the IV infusion:

5 minutes and 15 minutes after nivolumab dose

5 minutes, 15 minutes, 30 minutes, and 1 hour after HuAB1 dose

15 minutes (±5 minutes) post-HuAB1 dose:

Blood collection for serum (for analyses described in Appendix D) withthe following exceptions:

HuAB1 and nivolumab PK for Cycle 8 only

4.2.3.8 Treatment Completion or Early Termination Visit

Patients will return to the study center approximately 28 (±7) daysafter their last infusion of HuAB1 and nivolumab, or in the event apatient discontinues prematurely from the study.

The following assessments will be performed:

Physical examination, including weight

Vital signs (blood pressure, pulse, respiratory rate, and temperature insupine position after 5 minutes rest; pulse oximetry at rest and afterexertion)

ECOG performance status evaluation

Clinical safety labs (as described in Appendix B, footnote h)

12-lead ECG

Radiological imaging: CT/MRI scan does not need to be repeated ifperformed within 8 weeks prior to the Treatment Completion/EarlyTermination Visit or if tumor progression was previously determined.

Serum pregnancy test (β-HCG)

Optional biopsy for patients who progressed (for analyses described inAppendix D)

Blood collection

Serum (for analyses described in Appendix D)

Whole blood (for CD14⁺/CD16⁺ monocyte analysis only)

AE reporting, if applicable

Review of concomitant medications

4.2.4 Follow-Up and Survival Follow-Up for all Patients

After the Study Treatment Discontinuation Visit, each ongoing AE shouldbe followed until the event has resolved to baseline grade, the event isassessed by the Investigator as stable, the patient is lost tofollow-up, the patient withdraws consent, or when it has been determinedthat the study treatment is not the cause of the AE.

The occurrence of SAEs will be collected until 100 days after the lastdose of study treatment or until resolved. Thereafter, only SAEsdetermined by the Investigator to be related to the study treatment willbe collected.

In addition, serum will also be collected 100 days after last dose toanalyze for HuAB1 PK, HuAB1 ADA, and nivolumab ADA.

Patients who have discontinued study treatment for reasons other thandisease progression will continue to undergo tumor assessmentsapproximately every 8 weeks (±2 weeks) from Study TreatmentDiscontinuation Visit until disease progression.

After the Study Treatment Discontinuation Visit, all patients(regardless of reason for discontinuation) will have anti-cancertherapies recorded and will be followed for survival every 3 monthsuntil death, loss to follow-up, withdrawal of consent, or studytermination by the Sponsor.

For patients who withdraw their consent from the study but agree toparticipate in the survival follow-up, only survival information will becollected every 3 months.

4.3 Study Assessments 4.3.1 Safety Assessments

At baseline, a medical history will be obtained to capture relevantunderlying conditions. The baseline examinations should include weight,height, ECOG Performance Status (Appendix G), ECG, blood pressure (BP),heart rate (HR), temperature, and oxygen saturation by pulse oximetry atrest (also monitor amount of supplemental oxygen, if applicable) within28 days prior to first dose.

Safety assessments including serum hematology, chemistry, ECOG, weightand other assessments including ECG (if clinically indicated) will bedone as part of standard care during each visit prior to dosing as notedin Appendices A, B, and C. The patient will also be monitored for anyinfusion-related AEs during dosing and followed up accordingly based onprotocol guidelines. Pre-medications including steroids, antihistaminesor other treatments will be given prior to future dosing if the patientdevelops infusion reactions per protocol guidelines.

Any patient who has received study drug will be evaluated for safety.Toxicity assessments will be continuous during the treatment phase andfollow-up visits in-person. Once patients reach the survival follow-upphase, documented telephone calls/email correspondence to assess thepatient's status are acceptable.

AEs and laboratory values will be graded according to the NCI CTCAEv4.03

Oxygen saturation by pulse oximetry at rest (also monitor amount ofsupplemental oxygen, if applicable) should be assessed at each on-studyvisit prior to dosing. If a patient shows changes on pulse oximetry orother pulmonary-related signs (hypoxia, fever) or symptoms (e.g.dyspnea, cough, fever) consistent with possible pulmonary AEs, thepatient should be immediately evaluated to rule out pulmonary toxicity,according to the suspected pulmonary toxicity management table inAppendix E.

Physical examinations are to be performed as clinically indicated. Ifthere are any new or worsening clinically significant changes since thelast exam, report changes on the appropriate non-serious AE or SAE page.

Additional measures, including non-study required laboratory tests,should be performed as clinically indicated or to comply with localregulations. Laboratory toxicities (e.g., suspected drug induced liverenzyme evaluations) will be monitored during the follow-up phase via onsite/local labs until all study drug-related toxicities resolve, returnto baseline, or are deemed stable.

Some of the assessments referred to in this section may not be capturedas data in the CRF. They are intended to be used as safety monitoring bythe treating physician. Additional testing or assessments may beperformed as clinically necessary or where required by institutional orlocal regulations.

4.3.2 Efficacy Assessments 4.3.2.1 Primary Efficacy Parameters

The primary efficacy parameter is the objective response rate (ORR;number of patients with confirmed response of CR or PR, divided by thetotal number of treated patients with measurable disease at baseline).Tumor response status will be assessed using RECIST v1.1 (Appendix F).Independent review of tumor assessments may be requested at thediscretion of the Sponsor.

4.3.2.2 Additional Efficacy Parameters

Additional efficacy parameters may include the following: OverallSurvival (OS, 1-year OS, and median OS), progression-free survival(PFS), and duration of response (DOR) for those patients with confirmedresponses, based on RECIST v1.1.

CT/MRI (chest, abdomen, pelvis, and brain) will be performed atScreening, during the treatment and at the end of study/earlytermination per protocol. Measurements of change in tumor burden must bereviewed and documented after each measurement.

4.3.2.3 Tumor Biopsy

Biopsy at the primary tumor site will be collected at screening and alsoat 29 days on-treatment (prior to Cycle 3, Day 1) for all Phase 1apatients and 10 patients per cohort in Phase 1b. Patients in the Phase1a portion of the study will also have post-treatment biopsy upondocumented tumor progression. This post-progression biopsy will beoptional for patients in Phase 1b. Biopsies will be assessed for tumorassociated leukocytes, tumor proliferation, and cell death markers.

4.3.3 Pharmacokinetic Assessments

Blood samples for the PK evaluation of both HuAB1 and nivolumab will becollected from all patients (Phase 1a and 1b).

Blood samples will be collected for measurement of serum HuAB1concentration during Cycle 1 on Days 1, 2, 4, and 8. Blood samples willbe collected both before and at the end of the infusion for Cycle 2. Inaddition, blood samples will be collected at the end of the infusion forCycle 8 and before the infusion on Cycles 3, 5, 9, 13, and 21. A bloodsample will also be collected for PK analysis 100 days post-last doseand at the Treatment Completion/Early Termination visit.

Patients enrolled in dose escalation of phase 1a and phase 1b will haveblood sampling for measurement of serum nivolumab concentration bothbefore and at the end of infusion for Cycle 1. In addition, bloodsamples will be collected prior to infusion of Cycles 2, 3, 5, 9, 13,and 21. A blood sample will also be collected for PK analysis 100 dayspost-last dose and at the Treatment Completion/Early Termination visit.

Standard PK parameters will be determined based on serum HuAB1concentration-time data, as appropriate. Potential pharmacokineticdrug-drug interaction between HuAB1 and nivolumab will be evaluated.

4.3.3.1 Pharmacokinetic Collection and Processing

Blood samples will be collected and processed for serum according to theinstructions provided in a separate Laboratory Manual.

4.3.3.2 Pharmacokinetic Sample Analysis

HuAB1 concentration in serum will be determined in serum using avalidated ELISA method. Nivolumab concentration in serum will bedetermined in serum using a validated ECLA method.

4.3.4 Immunogenicity Assessments

Blood samples will be collected before the infusion on Cycles 1, 2, 3,5, 13, and 21, at 100 days post-last dose and at the TreatmentCompletion/Early Termination visit to measure ADA for HuAB1 andnivolumab. ADA for HuAB1 in serum will be measured by a validatedbridging ECLA that utilizes Meso Scale Discovery (MSD) technology. ADAfor nivolumab in serum will be measured by a validated ECLA method.

4.3.5 Biomarker Assessments

A variety of factors that could potentially predict clinical response tothe combination of HuAB1 and nivolumab will be investigated in allperipheral blood and in tumor specimens taken from patients prior to andduring treatment. Data from these investigations will be evaluated forassociations with response and/or safety (AE) data. In addition,analyses of markers between the treatment arms will provide thenecessary data to identify and validate biomarkers with predictive vsprognostic value. Complete instructions on the collection, processing,handling and shipment of all samples described herein will be providedin a Biomarker Manual.

4.3.5.1 Tumor Tissue Specimens

Tumor tissue specimens in the form of a paraffin embedded block orunstained slides will be submitted for central IHC assessment. Thesebiopsy samples should be excisional, incisional or core needle as fineneedle aspirates or other cytology specimens are insufficient fordownstream biomarker analyses. Tissue samples are being collected toevaluate the PD effect of study drugs on the tumor microenvironment.These samples may also undergo gene sequencing to determine the effectof study drugs on gene pathways as well as identified gene signaturesassociated with resistance to response. These analyses may help predictfuture response to treatment. A summary of analyses to be performed aredescribed in Appendix D.

Tumor biopsy specimens will be obtained before treatment, as well ason-treatment, to examine immune infiltrates and expression of selectedtumor markers. The tumor tissue that is obtained from these samples willbe divided as appropriate between a fresh frozen sample to be used forgene expression analysis, and a formalin fixed sample to be used forIHC.

Stained tissue sections will be submitted to the central lab, where theywill be assessed by a pathologist and scored for PD-L1 positivity.

Samples may be assessed for the expression of immune or disease relatedgenes, RNAs and/or proteins, as well as for the presence of immune cellpopulations using a variety of methodologies inclusive of, but notlimited to IHC, qRT-PCR, genetic mutation detection and fluorescent insitu hybridization (FISH). Other methods of tumor biomarker expressionare being evaluated.

4.3.5.2 Serum

Blood samples for exploratory serum biomarker analyses will be drawn atthe time points indicated in the Schedule of Assessments (Appendices A,B, and C). Blood samples will be processed to collect serum and then putin frozen storage prior to analysis. In addition to the PK and ADAanalyses mentioned above, serum samples will be analyzed to determinethe PD effect of study drugs on cytokine and CSF1R ligandconcentrations. Samples may be assessed by ELISA, seromics and/or otherrelevant multiplex-based protein assay methods. Serum marker analysesmay also help establish a biomarker signature that may predict benefitor correlate with efficacy that can be used to inform this and futurestudies. Timings of sample collection are listed in Appendix C andanalyses to be performed are described in Appendix D.

4.3.5.3 Whole Blood for Single Nucleotide Polymorphism (SNP) Assessment

Whole blood samples for exploratory pharmacogenetic assessment will becollected from all patients and put in frozen storage prior to analysis.Genomic DNA will be extracted and subsequently assessed for singlenucleotide polymorphisms and other genetic variations in candidate genesthat may predispose patients to benefit or AEs. Additional use of thesedata may include correlative analyses aimed at identifying genotypicassociations with clinically-relevant biomarkers identified by othermethodologies described in this section.

4.3.5.4 Flow Cytometry

Pre-treatment and on-treatment samples will be analyzed by flowcytometry to study the effects of HuAB1 and nivolumab on variousperipheral blood immune cell subsets. Whole blood samples will beassessed to confirm the predicted PD effect of HuAB1 on the reduction ofCD16⁺ monocytes. PBMC samples will be analyzed to determine whetherblockade of PD-1 combined with CSF1R targeting will impact peripheral Tcell activation and function. PBMC samples may be assessed for thelevels of myeloid-derived suppressor cells and for monocyte phenotype.Timings of sample collection are listed in Appendix C and analyses to beperformed are described in Appendix D.

4.3.5.5 Gene Expression Profiling

Alterations in the pattern of gene expression in tumor samples will beassessed, using RNA sequencing and qPCR, with particular emphasis onpathways of immune function. All samples collected will be stored, andmay be used for subsequent research relevant to tumor immune response.

5 Statistical Considerations

All analyses will be descriptive and will be presented by dose group andoverall as appropriate. Data collected in this study will be presentedusing summary tables and patient data listings. Continuous variableswill be summarized using descriptive statistics, specifically the mean,median, standard deviation, minimum, and maximum. Categorical variableswill be summarized by frequencies and percentages.

5.1 Sample Size Determination

Approximately 30 patients will be enrolled in Phase 1a (doseescalation); between 3 and 6 patients are expected to be treated at eachdose escalation cohort according to the algorithm outlined in FIG. 6.Table 5 summarizes the probability of escalating to the next dose cohortfor various true DLT rates.

TABLE 5 Probability of Dose Escalation and Dose Limiting Toxicities TrueDLT rate 1% 5% 10% 30% 50% Probability of 0.999 0.973 0.906 0.494 0.172dose escalation

Objective Response Rate is the primary efficacy variable for the Phase1b portion of the study. With approximately 30 patients in each diseasetype, the 95% confidence interval half-width for the correspondingresponse rate would be within 18%.

5.2 Populations for Analyses

All Enrolled Population: All patients who sign the ICF and wereregistered in IXRS.

Safety Population: All patients who receive at least one dose of HuAB1and/or nivolumab.

PK Population: All patients who receive at least one dose of HuAB1 andhave available serum concentration data evaluable for the determinationof PK profile. All patients who received at least one dose of nivolumab,the peak and trough PK profile will be determined.

Biomarker Patients: All patients who receive at least one dose of HuAB1and/or nivolumab and have available biomarker data.

Immunogenicity Patients: All patients who receive at least one dose ofHuAB1 and/or nivolumab and have available ADA data.

5.3 Endpoints 5.3.1 Phase 1a Endpoints 5.3.1.1 Primary

Safety

The incidence of Grade 3 and Grade 4 AEs and clinical laboratoryabnormalities defined as DLTs.

The incidence of AEs, clinical laboratory abnormalities, and ECGabnormalities

5.3.1.2 Secondary

Pharmacokinetic

The following PK parameters will be derived from concentration-time datafor HuAB1 when appropriate and applicable. Other parameters, such asdose dependency and accumulation ratio, may also be calculated. Thepotential pharmacokinetic drug-drug interaction between HuAB1 andnivolumab will be assessed as appropriate.

Area under serum concentration-time curve (AUC)

Maximum serum concentration (C_(max))

Minimum serum concentration (C_(min))

Volume of distribution at steady state (V_(ss))

The peak and trough concentration PK profile will be derived fromnivolumab serum concentration data when appropriate and applicable.

Immunogenicity

Immunogenicity, defined as an immune response to either HuAB1 ornivolumab, will be assessed by measurement of total anti-HuAB1antibodies and total anti-nivolumab antibodies from all patients.Immunogenicity testing will consist of screening, confirmation, andtitration for both HuAB1 and nivolumab.

Pharmacodynamic Biomarkers

Changes in whole blood monocyte subsets by flow cytometry

Changes in cytokine levels multiplex analysis

Biomarker expression levels in tumor biopsy samples as measured by IHC

5.3.1.3 Exploratory

Pharmacodynamic Biomarkers

Changes in serum levels of selected markers

Changes in peripheral T cell and other leukocyte phenotypes by flowcytometry

Levels of peripheral MDSC by flow cytometry

Changes in gene expression in whole blood or PBMC

5.3.2 Phase 1b Endpoints 5.3.2.1 Primary

Efficacy

The objective response rate (ORR) will be defined as the total number ofpatients with confirmed responses of either CR or PR divided by thetotal number of response—evaluable patients

Safety

The incidence of AEs, SAES, clinical laboratory abnormalities, and ECGabnormalities

The incidence of treatment discontinuations, modifications,interruptions due to adverse events

Grade 3 and Grade 4 AEs and clinical laboratory abnormalities

5.3.2.2 Secondary

Pharmacokinetic

The following PK parameters will be derived from concentration-time datafor HuAB1 when appropriate and applicable. Other parameters, such asdose dependency and accumulation ratio, may also be calculated. Thepotential pharmacokinetic drug-drug interaction between HuAB1 andnivolumab will be assessed as appropriate.

Area under serum concentration-time curve (AUC)

Maximum serum concentration (C_(max))

Minimum serum concentration (C_(min))

Volume of distribution at steady state (V_(ss))

The peak and trough concentration PK profile will be derived fromnivolumab serum concentration data when appropriate and applicable.

Immunogenicity

Immunogenicity, defined as an immune response to either HuAB1 ornivolumab, will be assessed by measurement of total anti-HuAB1antibodies and total anti-nivolumab antibodies from all patients.Immunogenicity testing will consist of screening, confirmation, andtitration for both HuAB1 and nivolumab.

Pharmacodynamic Biomarkers

Changes in whole blood monocyte subsets by flow cytometry

Changes in cytokine levels multiplex analysis

Biomarker expression levels in tumor biopsy samples as measured by IHC

Efficacy

Overall Survival (OS) will be defined as the time between the first doseof study drug and death.

One-year OS

Median OS

Duration of response (DOR) will be defined as the time from response (CRor PR) until the onset of PD that is subsequently confirmed.

Progression-free survival (PFS) will be defined for each patient as thetime from the first dose to the first observation of disease progressionor death due to any cause.

5.3.2.3 Exploratory

Pharmacodynamic Biomarkers

Changes in serum levels of selected markers

Changes in peripheral T cell and other leukocyte phenotypes by flowcytometry

Levels of peripheral MDSC by flow cytometry

Changes in gene expression in whole blood or PBMC

5.4 Analyses 5.4.1 Demographics and Baseline Characteristics

Demographic data, medical history, other baseline characteristics,concomitant disease, and concomitant medication will be summarized bycohort and overall. To determine whether the criteria for study conductare met, corresponding tables and listings will be provided. These willinclude an assessment of protocol deviations, study drug accountability,and other data that may impact the general conduct of the study.

5.4.2 Efficacy Analyses

For each disease type, response to treatment will be summarized by ORR,defined as the ratio of the number of patients that achieve an objectiveresponse to the number of patients enrolled. Exact confidence intervalwill be constructed for the response rate. Overall Survival, survival at1 year, and median survival will be estimated by the Kaplan-Meiermethod. The corresponding confidence interval will also be presented.

5.4.3 Safety Analyses

Safety analyses will be performed for patients included in the safetypopulation. AEs, clinical laboratory information, vital signs, ECOGperformance status, weight, and ECGs will be tabulated and summarized.

AEs will be summarized overall and with separate summaries for SAEs, AEsleading to discontinuation, AEs leading to death, and NCI-CTCAE version4.03 Grade 3 or higher AEs.

Weight and vital signs will be summarized descriptively (n, mean,standard deviation, median, minimum, and maximum). ECOG performancestatus will be summarized categorically and descriptively.

Shift tables displaying patient counts and percentages classified bybaseline grade and maximum grade on treatment will be provided forlaboratory data by cohort and overall. A marked laboratory change isdefined as a shift from a baseline Grade 0 to Grade 3 (non-hematologic)or Grade 4 (hematologic) on treatment, or a shift from a baseline Grade1 to Grade 4 on treatment. The number and percentage of patients withmarked laboratory changes will be tabulated by cohort and overall.

5.4.4 Pharmacokinetic Analyses

Individual and mean serum concentration of HuAB1 and nivolumab versustime data will be plotted by dose level. Summary statistics will betabulated for the serum concentration-time data and estimated PKparameters of HuAB1, as appropriate. Potential PK drug-drug interactionbetween HuAB1 and nivolumab will be evaluated.

For HuAB1, PK parameters including C_(max), AUC, C_(trough), CL, andV_(ss) will be estimated. Other PK parameters as well as inter-patientvariability, HuAB1 accumulation and dose proportionality will beevaluated when data are available. PK data (HuAB1 and/or nivolumab)collected from this study may be used in combination with other studiesfor exposure-response or population PK modeling, which will be part of aseparate report.

5.4.5 Immunogenicity

A listing will be provided of all available immunogenicity data for bothHuAB1 and nivolumab. Additionally, a listing of immunogenicity data fromthose patients with at least one positive ADA at any time point will beprovided by dose level. The frequency of patients with at least onepositive ADA assessment, and frequency of patients who develop ADA aftera negative baseline assessment will be provided by dose. To examine thepotential relationship between immunogenicity and safety, the frequencyand type of AEs of special interest may be examined by overallimmunogenicity status. Associations between pre-dose concentrations ofHuAB1 or nivolumab and corresponding ADA assessments may be explored.

5.4.6 Biomarker Analyses

To assess the PD effects of HuAB1 and nivolumab on various exploratorybiomarkers (such as soluble factors, peripheral blood immune cellsubsets, and other markers as assessed by IHC) summary statistics forthese markers and their changes (or percent changes) from baseline willbe tabulated by visit and dose. In addition, the time course ofexploratory biomarker outcomes will be investigated graphically, bysummary plots or individual patient plots over time. Patterns of changein these biomarker values over time and how the patterns differed amongdose levels may be additionally investigated using appropriate modeling,for example, by linear mixed effects models.

Possible associations of biomarker measures with clinical efficacymeasures including OS will be investigated based on data availability.Methods such as, but not limited to, logistic regression may be used tofurther investigate such associations.

If, at the time of database lock for the primary and secondaryendpoints, biomarker data related to the exploratory objectives are notavailable, these biomarker analyses results may not be included in theCSR but reported separately.

Selected Serum Marker Expression:

Analyses of expression are descriptive in nature and intended to examinethe distribution of expression and assess potential associations betweenexpression and efficacy measures. If there is an indication of ameaningful association, future work will evaluate expression as apredictive biomarker, including selection of an optimal expressioncut-off to classify patients as positive or negative. Cut-off selectionand validation will be conducted across studies and reported outside ofindividual CSRs. Additionally, analyses detailed below may be reportedoutside of the CSR in order to ensure the integrity of any potentialvalidation analyses using data from this study.

The following analyses will be performed:

Listing of selected biomarker data

Summary of tumor specimen acquisition and characteristics

Summary statistics of expression by select subgroups, and overall

Box plot of expression by treatment group and overall

OS curves for each treatment group will be estimated using theKaplan-Meier (KM) product limit method for each Expression Quartilesubgroup and for the subgroup of patients with an unknown orindeterminate IHC result. Expression quartiles will be defined based onoverall population. Two-sided, 95% confidence intervals for median OSwill be computed by Brookmeyer and Crowley method.

Investigator-determined PFS curves for each treatment group will beestimated using the KM product-limit method for each Expression Quartilesubgroup and for the subgroup of patients with an unknown orindeterminate IHC result. Expression quartiles will be defined based onoverall population. Two-sided, 95% confidence intervals for median PFSwill be computed by Brookmeyer and Crowley method.

Investigator-determined ORRs will be computed by treatment group alongwith exact 95% CIs using the Clopper-Pearson method for each ExpressionQuartile subgroup and for the subgroup of patients with an unknown orindeterminate expression result. Expression quartiles will be definedbased on overall population. Associated odds ratios and 95% CIs will becalculated.

Box plots of expression versus Response Status by treatment group

Cumulative distribution plot of expression versus population percentileby treatment group and overall

Waterfall plots of individual expression by treatment group

Forest plot of OS and PFS Hazard Ratios with 95% CIs for each ExpressionQuartile subgroup and for the subgroup of patients with an unknown orindeterminate IHC result. Expression Quartiles will be defined based onoverall population.

5.5 Interim Analysis

No formal interim analysis is planned.

The Sponsor (and/or designee) and Investigator(s) will review safetydata from each dose cohort prior to dose escalation or de-escalation. Inaddition, an interim data summary may be performed at several timesprior to completion of the study in order to facilitate programdecisions and to support presentations or publications.

Term Definition ACTH Adrenocorticotropic hormone ADA Anti-drug antibodyAE Adverse event ALT Alanine aminotransferase ANA Antinuclear antibodyANC Absolute neutrophil count AST Aspartate aminotransferase ATAminotransferases AUC Area under the concentration-time curve AUC(INF)Area under the concentration-time curve from time zero extrapolatedβ-HCG Beta-human chorionic gonadotropin BID Bis in die; twice daily BMIBody mass index BMS Bristol-Myers Squibb BP Blood pressure BTLA B- andT-lymphocyte attenuator BUN Blood urea nitrogen ° C. Degrees Celsius CBCComplete blood count CD Cluster of differentiation CFR Code of FederalRegulations CHO Chinese hamster ovary CI Confidence interval CKCreatinine kinase CL Clearance C_(max), CMAX Maximum observedconcentration C_(min), CMIN Trough observed concentration CMVCytomegalovirus CNS Central nervous system CR Complete response CRCColorectal cancer CRF Case report form, may be paper or electronic CROContract research organization CRP C-reactive protein CSF1 Colonystimulating factor 1 CSF1R Colony stimulating factor 1 receptor CSRClinical study report CT Computed tomography CTA Clinical trialsagreement CTCAE v4.03 Common Terminology Criteria for Adverse Events,version 4.03 CTLA-4 Cytotoxic T lymphocyte antigen 4 C_(trough) Troughobserved plasma concentration CTX C-terminal collagen crosslink peptidesCV Coefficient of variation DC Dendritic cell DEHPDi-(2-ethylhexyl)phthalate DILI Drug-induced liver injury dL DeciliterDLT Dose-limiting toxicity DMARD Disease-modifying anti-rheumatic drugDNA Deoxyribonucleic acid DOR Duration of response EC₅₀ Half-maximaleffective concentration ECG electrocardiogram ECLAElectrochemiluminescence assay ECM Extracellular matrix ECOG EasternCooperative Oncology Group eCRF Electronic case report form EDCElectronic data capture e.g. exempli gratia (for example) ELISAEnzyme-linked immunosorbent assay ePPND Enhanced pre- and post-nataldevelopment ESR Erythrocyte sedimentation rate ° F. Degrees FahrenheitFACS Fluorescent-activated cell sorter Fc Fragment crystallizable FDAFood and Drug Administration FFPE Formalin-fixed, paraffin-embedded FISHFluorescent in situ hybridization FivePrime Five Prime Therapeutics,Inc. FSH Follicle stimulating hormone g Gram GBM Glioblastoma multiformeGCP Good Clinical Practice GI Gastrointestinal h Hour HBcAg Hepatitis Bcore antigen HBsAg Hepatitis B surface antigen HBV Hepatitis B virus HCVHepatitis C virus HIV Human Immunodeficiency Virus HR Heart rate HRPHorseradish peroxidase HRT Hormone replacement therapy IB Investigator'sBrochure IC₅₀ Half-maximal inhibitory concentration ICD ImplantableCardioverter Defibrillator ICF Informed consent form ICH InternationalConference on Harmonisation ICOS Inducible co-stimulator ID Infectiousdisease i.e. id est (that is) IEC Independent ethics committee IFNInterferon IgG Immunoglobulin G IHC Immunohistochemistry IL InterleukinIM Intramuscular IMP Investigational medicinal product INDInvestigational new drug INR International normalized ratio I-OImmuno-oncology irAE Immune-related adverse event IRB Institutionalreview board ITIM Immunoreceptor tyrosine inhibitory motif ITSMImmunoreceptor tyrosine-based switch motif IU International unit IVIntravenous IXRS Integrated voice and web response system kg Kilogram KMKaplan-Meier LAG-3 Lymphocyte-activate gene 3 LDH Lactate dehydrogenaseLFT Liver function test LLOQ Lower limit of quantification MABEL Minimumanticipated biological effect level mCRPC Metastaticcastration-resistant prostate cancer MDSC Myeloid-derived suppressorcell mg Milligram min Minute μL Microliter mL Milliliter MLR Mixedlymphocyte reaction μM Micrometer mM Millimolar mm³ Cubic millimetersmmHg millimeters of mercury MRI Magnetic resonance imaging MSD MesoScale Discovery MTD Maximum tolerated dose N Number of patients orobservations NCA Non-compartmental analysis NCI National CancerInstitute ng Nanogram NOAEL No-observable-adverse-effect level NSCLCNon-small cell lung cancer NYHA New York Heart Association NSAIDNon-steroidal, anti-inflammatory drug ORR Objective response rate OSOverall survival PBMC Peripheral blood mononuclear cell PDPharmacodynamics PD-1 Programmed death 1 PDAC Pancreatic ductaladenocarcinoma PD-L1 Programmed death ligand 1 PD-L2 Programmed deathligand 2 PFS Progression-free survival PK Pharmacokinetics PO Per os; bymouth PPK Population pharmacokinetics PR Partial response PTT (aPTT)Partial thromboplastin time PVC Polyvinyl chloride q2w Every two weeksqPCR Quantitative real-time polymerase chain reaction qRT-PCRQuantitative reverse-transcription polymerase chain reaction QTcFFridericia's correction formula for QT interval RBC Red blood cell RCCRenal cell carcinoma RD Recommended Dose RECIST v1.1 Response EvaluationCriteria in Solid Tumors, version 1.1 RNA Ribonucleic acid SAE Seriousadverse event SAP Statistical analysis plan SCCHN Squamous-cellcarcinoma of the head and neck SD Stable disease SkTnI Skeletal troponinSOP Standard operating procedure T₃ Triiodothyronine T₄ Thyroxine TAMTumor-associated macrophage TB Tuberculosis TCR T-cell receptor TILTumor-infiltrating lymphocyte T_(max), TMAX Time of maximum observedconcentration TNF Tumor necrosis factor Trap5b Tartrate resistant acidphosphatases 5b ULN Upper limit of normal USP United States PharmacopeiaVss Volume of distribution at steady state Vz Volume of distribution ofterminal phase (if IV and if multi- WBC White blood cell WHO WorldHealth Organization WOCBP Women of childbearing potential

6 References

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APPENDIX A Schedule of Assessments Phase 1a HuAB1 Monotherapy andCombination - Schedule of Patient Assessments Treatment ScreeningCompletion/ Day-28 Cycle 1 Cycle 2 Cycle x^(r) Early to Day 0 Day 1 Day2 Day 4 Day 8 Day 1 Day 1 Termination Procedure^(a, b) Week 0 Week 1Week 2 Week 3 Week ≥ 5 Visit Informed Consent x Review/ConfirmEligibility x x Medical History/ x x Physical Examination^(c) x x x x xx Height and Weight^(d) x x x x x Vital Signs^(e) x x x x x x ECOGPerformance Status^(f) x x x x x Screening Labs^(g) x Clinical SafetyLabs^(h) x x x x x x 12-Lead ECG^(i) x x CT/MRI Tumor Assessment^(j,k) xx x Serum Pregnancy Test^(l) x x x Biopsy^(m) x x x PK Sampling^(n,o) xx x x x x x PD Sampling^(n) x x x x x x x ADA Sampling^(n) x x x x ANATesting^(p) x x x x Study Drug(s)^(q) x x x Adverse Eventsx - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - x xPrior/Concomitantx - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - x xNotes for Phase 1a Schedule of Assessments ^(a)Unless specified,procedure is to be completed within ± 72 hours of scheduled time pointand to be synchronized with administration day of HuAB1 infusion.^(b)Any clinical assessment, laboratory study, or additionalnon-specified tests may be obtained at any time, if clinicallyindicated. ^(c)Standard physical examination will be performed asdetermined by the Investigator, particularly to follow physical findingsto resolution. Targeted physical exams should be conducted at any timeto follow up on AE reports. ^(d)Height is only required to be recordedat Screening (for BMI calculation). Weight is required to be recorded atDay 1 of each cycle. Dose will be adjusted only if weight change is >10%from first dose on Cycle 1 Day 1. ^(e)Vital signs include pulse,respiratory rate, blood pressure, and temperature in the supineposition. Measure prior to dose and after completion of each IV infusionat the following time points: 5 minutes, 15 minutes, 30 minutes, and 1hour post-dose (30 minutes and 1 hour after HuAB1 only). Pulse oximetryis performed at rest and after exertion prior to dosing only.^(f)Patient ECOG Status assessments are to be performed within 72 hoursprior to dosing (Day 1 of each cycle). ^(g)Screening labs includeserology for Hepatitis B (HBsAg and HBcAb), Hepatitis C (HCV antibody),HIV antibody, and Quantiferon test (for latent TB). ^(h)Clinical SafetyLabs: Hematology including CBC with differential, platelets, hemoglobin,hematocrit, RBC, and RBC indices Chemistry includes CK (creatininekinase), AST (aspartate transaminase), ALT (alanine transaminase),bicarbonate, bilirubin, (direct and total), BUN (blood urea nitrogen),calcium, chloride, creatinine, glucose, LDH (lactate dehydrogenase),phosphorus, potassium, sodium, and, if applicable, serum pregnancy. IfCK is elevated at any time, obtain troponins (cardiac and skeletal), CKisoenzymes, aldolase, and ECG; repeat CK and these additional testsdaily or other interval as clinically indicated, until resolved orstable. If either AST or ALT is elevated, obtain total serum bilirubin,alkaline phosphatase; repeat daily or other interval, as clinicallyindicated, until resolved or stable. Additional tests may be obtained atany time, if clinically indicated. Urinalysis will only be done atScreening, and when clinically indicated. ^(i)Obtain ECG records atScreening and Treatment Completion/Early Termination Visit (after PKblood draw, record exact time). Additional ECGs should be obtained atany time, if serum CK or cardiac troponin is elevated; if abnormal(excluding sinus tachycardia), ECGs should be obtained (if clinicallyindicated), until the abnormality is resolved or clinically stable.Additional ECGs may be obtained at any time, if clinically indicated.ECGs for each patient should be obtained from the same machine wheneverpossible. To minimize variability, it is important that patients be in aresting position for at least 5 minutes prior to each ECG evaluation.Body position should be consistently maintained for each ECG evaluationto prevent changes in heart rate. Environmental distractions (e.g.,television, radio, conversation) should be avoided during the pre-ECGresting period and during ECG recording. ^(j)CT/MRI of the Tumor sitesmeasured as per Response Evaluation Criteria in Solid Tumors (RECIST)v1.1. If patient terminates prior to scheduled CT/MRI scans, subjectshould have scans done at Treatment Completion/Early Termination Visit.The same measuring modality should be used by the site to maintainconsistency across the various time points. ^(k)Performed every 8 weeksfor the first 12 months for patients who remain on treatment (and every12 weeks thereafter) and 28 days (± 7 days) after the last dose of studytreatment. CT/MRI scans do not need to be repeated if performed within 8weeks prior to the Treatment Completion/Early Termination Visit or iftumor progression was previously determined. ¹All women of childbearingpotential (including those who have had a tubal ligation) will have aserum pregnancy test at Screening, on Cycle 1 Day 1, and at TreatmentCompletion/Early Termination Visit and when clinically indicated.^(m)Biopsy at primary tumor or metastatic tumor site will be collectedat Screening and prior to Cycle 3, Day 1 dose. It is recommended thatpatients who have documented progression receive another biopsy at theend of treatment. Biopsies will be assessed for tumor associatedleukocytes, tumor proliferation and cell death markers. ^(n)Samples willbe collected for PK, PD, and ADA analyses. Not all visits will requirecollection of all three-see Appendix C for collection schedule.^(o)Blood will be collected to evaluate Cmax & Cmin on day 1 of studydrugs on Cycles 1, 2, 3, 5, 8, 9, 13, 21, and at the end of treatment.^(p)Antinuclear antibody (ANA) testing by indirect fluorescent antibody(IFA). If the titer is positive, check erythrocyte sedimentation rate(ESR) and C-reactive protein (CRP) to confirm result. Will be checkedprior to dose at Cycles 1, 2, 3, 5, 9, 13, 21, then every 6 cycles whileon treatment and at Treatment Completion/Early Termination Visit.^(q)HuAB1 +/− nivolumab study drug will be administered every 2 weeks in14-day cycles for 4 weeks. The dosing may continue until PD orunacceptable toxicity. ^(r)These assessments are to be performed priorto each subsequent dose (with the exceptions noted in Appendix B) forthose patients who continue treatment without signs of progressivedisease or toxicity

APPENDIX B Schedule of Assessments Phase 1b HuAB1 + Nivolumab - Scheduleof Patient Assessments Treatment Screening Completion/ Day-28 Cycle 1Cycle 2 Cycle x^(s) Early to Day 0 Day 1 Day 2 Day 4 Day 8 Day 1 Day 1Termination Procedure^(a, b) Week 0 Week 1 Week 2 Week 3 Week ≥ 5 VisitInformed Consent x Review/Confirm Eligibility x x Medical History/ x xDemographics Physical Examination^(c) x x x x x x Height and Weight^(d)x x x x x Vital Signs^(e) x x x x x x ECOG Performance Status^(f) x x xx x Screening Labs^(g) x x Clinical Safety Labs^(h) x x x x x x 12-LeadECG^(i) x CT/MRI Tumor Assessment^(j,k) x x x Serum Pregnancy Test^(l) xx x Biopsy^(m) x x x PK Samplinen^(n,o) x x x x x x x PD Sampling^(n) xx x x x x x ADA Sampling^(n) x x x x ANA Testing^(p) x x x x StudyDrug(s)^(q,r) x x x Adverse Eventsx - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - x xPrior/Concomitant Medicationsx - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - x xNotes for Phase 1b Schedule of Assessments ^(a)Unless specified,procedure is to be completed within ± 72 hours of scheduled time pointand to be synchronized with administration day of HuAB1 infusion.^(b)Any clinical assessment, laboratory study, or additionalnon-specified tests may be obtained at any time, if clinicallyindicated. ^(c)Standard physical examination will be performed asdetermined by the Investigator, particularly to follow physical fmdingsto resolution. Targeted physical exams should be conducted at any timeto follow up on AE reports. A photo of the subject's eyes will be takenat baseline, and subsequently at follow up visits, as clinicallyindicated. ^(d)Height is only required to be recorded at Screening (forBMI calculation). Weight is required to be recorded at Day 1 of eachcycle. Dose will be adjusted only if weight change is >10% from firstdose. ^(e)Vital signs include pulse, respiratory rate, blood pressure,and temperature in the supine position. Measure prior to dose and aftercompletion of the IV infusion at the following time points: 5 minutes,15 minutes, 30 minutes, and 1 hour post-dose (30 minutes and 1 hour forHuAB1 only). Pulse oximetry is performed at rest and after exertionprior to dosing only. ^(f)Patient ECOG Status assessments are to beperformed within 96 hours prior to dosing (Day 1 of each cycle).^(g)Screening labs include serology for Hepatitis B (HBsAg and HBcAb),Hepatitis C (HCV antibody), HIV antibody, and Quantiferon test (forlatent TB). ^(h)Clinical Safety Labs: Hematology including CBC withdifferential, platelets, hemoglobin, hematocrit, RBC, and RBC indicesChemistry includes CK (creatinine kinase), AST (aspartate transaminase),ALT (alanine transaminase), bicarbonate, bilirubin, (direct and total),BUN (blood urea nitrogen), calcium, chloride, creatinine, glucose, LDH(lactate dehydrogenase), phosphorus, potassium, sodium, and, ifapplicable, serum pregnancy. If CK is elevated at any time, obtaintroponins (cardiac and skeletal), CK isoenzymes, aldolase, and ECG;repeat CK and these additional tests daily or other interval asclinically indicated, until resolved or stable. If either AST or ALT iselevated, obtain total serum bilirubin, alkaline phosphatase; repeatdaily or other interval, as clinically indicated, until resolved orstable. Additional tests may be obtained at any time, if clinicallyindicated. Urinalysis will only be done at Screening, and whenclinically indicated. ^(i)Obtain ECG records at Screening and TreatmentCompletion/Early Termination Visit (after PK/PD blood draw, record exacttime). Additional ECGs should be obtained at any time, if serum CK orcardiac troponin is elevated; if abnormal (excluding sinus tachycardia),ECGs should be obtained (if clinically indicated), until the abnormalityis resolved or clinically stable. Additional ECGs may be obtained at anytime, if clinically indicated. ECGs for each patient should be obtainedfrom the same machine whenever possible. To minimize variability, it isimportant that patients be in a resting position for at least 5 minutesprior to each ECG evaluation. Body position should be consistentlymaintained for each ECG evaluation to prevent changes in heart rate.Environmental distractions (e.g., television, radio, conversation)should be avoided during the pre-ECG resting period and during ECGrecording. Additional tests may be obtained at any time, if clinicallyindicated. ^(j)CT/MRI of the Tumor sites measured as per ResponseEvaluation Criteria in Solid Tumors (RECIST) v1.1. If subject terminatesprior to scheduled CT/MRI scan, subject should have scans done atTreatment Completion/Early Termination Visit. Response per CT/MRI willbe assessed using RECIST v1.1. In the case of PD-1 resistant melanomaand squamous lung cancer, CT scans need to be done at the end of Cycles4 and 6. The same measuring modality should be preferably used by thesite to maintain consistency across the various time points. The tumorassessments for all other cancer types will be done every 2 months (4cycles) apart unless clinically indicated. ^(k)Performed every 8 weeksfor the first 12 months for subjects who remain on treatment (and every12 weeks thereafter) and 28 days (± 7 days) after the last dose of studytreatment. CT/MRI scans do not need to be repeated if performed within 8weeks prior to the Treatment Completion/Early Termination Visit or iftumor progression was previously determined. ¹All women of childbearingpotential (including those who have had a tubal ligation) will have aserum pregnancy test at Screening and at Treatment Completion/EarlyTermination Visit and when clinically indicated. ^(m)Biopsy at primarytumor or metastatic tumor site will be collected at Screening and priorto Cycle 3, Day 1 dose. It is recommended that subjects who havedocumented progression receive another biopsy at the end of treatment.Biopsies will be assessed for tumor associated leukocytes, tumorproliferation and cell death markers. ^(n)Samples will be collected forPK, PD, and ADA analyses. Not all visits will require collection of allthree - see Appendix C for collection schedule. ^(o)Blood will becollected to evaluate Cmax & Cmin on day 1 of study drugs on Cycles 1,2, 3, 5, 8, 9, 13, 21, and at the end of treatment. ^(p)Antinuclearantibody (ANA) testing by indirect fluorescent antibody (IFA). If thetiter is positive, check erythrocyte sedimentation rate (ESR) andC-reactive protein (CRP) to confirm result. Will be checked prior todose at Cycles 1, 2, 3, 5, 9, 13, 21, then every 6 cycles while ontreatment and at Treatment Completion/Early Termination Visit. ^(q)HuAB1and nivolumab will both be administered by IV infusion over 30 minutes.Nivolumab will be given first, with a 30-minute rest between the 2infusions, followed by HuAB1 30- minute infusion. ^(r)HuAB1 + nivolumabstudy drug will be administered every 2 weeks in 14-day cycles and willcontinue until PD or unacceptable toxicity. ^(s)These assessments are tobe performed prior to each subsequent dose (with exceptions noted inAppendix B) for patients who continue treatment without signs ofprogressive disease or toxicity.

APPENDIX C Schedule of Sample Collection Phase 1a/b: Study Flowchart forPharmacokinetic and Pharmacodynamic Blood Sample Collections Study CycleStudy Day Time point Type of Sample Screening Screening Screening BiopsyTissue (Day-28) Cycle 1 Day 1 Prior to infusion HuAB1 & Nivo PK (serum)HuAB1 & Nivo ADA (serum) Selected serum markers (serum) ANA (serum)CD14⁺/CD16⁺ monocytes, MDSC panel (whole blood) Gene expression byRNAseq (whole Blood) T cell phenotype (frozen PBMC) Cytokine multiplexpanel (serum) 15 min after HuAB1 & Nivo PK (serum) infusion 4 hr afterHuAB1 PK (serum) infusion Day 2 24 hr after HuAB1 PK (serum) infusionGene expression by RNASeq (whole blood) Cytokine multiplex panel (serum)Day 4 72 hr after HuAB1 PK (serum) infusion CD14⁺/CD16⁺ monocytes,(whole blood) Gene expression by RNASeq (whole blood) Day 8 168 hr afterHuAB1 PK (serum) infusion CD14⁺/CD16⁺, (whole blood) Gene expression(whole blood) T cell phenotype (frozen PBMC) Cytokine multiplex panel(serum) Cycles 2-3 Day 1 Prior to infusion Biopsy Tissue (to be takenprior to Cycle 3, Day 1 dose) HuAB1 & Nivo PK(serum) HuAB1 & Nivo ADA(serum) Selected serum markers (serum) ANA (serum) CD14⁺/CD16⁺monocytes, (whole blood) Gene expression by RNAseq (whole blood) MDSCpanel (whole blood) (Cycle 3 only) T cell phenotype (frozen PBMC),(prior to Cycle 3 only; should correspond to tissue biopsy) Cytokinemultiplex panel (serum) 15 min after HuAB1 PK (serum) (Cycle 2 only)infusion Cycle 8 Day 1 15 min after HuAB1 PK and Nivo PK (serum)infusion Cycles 5, 9, 13, 21 Day 1 Prior to infusion HuAB1 and Nivo PK(serum) Selected serum markers (serum) (prior to Cycle 9) ANA (serum)(and every 6 cycles starting after Cycle 21) CD14⁺/CD16⁺ monocytes(whole blood) (prior to Cycle 9) Gene expression by RNASeq (whole blood)HuAB1 & Nivo ADA (serum) (prior to dose for cycles 5, 13, and 21)Cytokine multiplex panel (serum) (prior to dose for Cycles 9 and 21)Treatment Study Post treatment Biopsy tissue for patients who havedocumented disease progression Completion/ discontinuation/ HuAB1 & NivoPK (serum) Early PD HuAB1 & Nivo ADA (serum) Termination Selected serummarkers (serum) ANA (serum) CD14⁺/CD16⁺ monocytes, (whole blood)Cytokine multiplex panel (serum) Gene expression by RNASeq (whole blood)100 days post-last HuAB1 & Nivo ADA (serum) dose HuAB1 PK (serum)

APPENDIX D—SAMPLE COLLECTION FOR PD ANALYSES

-   -   Blood samples    -   Whole blood analyses    -   CD14⁺/CD16⁺ monocytes    -   Gene expression    -   DNA for SNP analysis    -   Serum analyses    -   PK of HuAB1    -   PK of nivolumab    -   ADA of HuAB1    -   ADA of nivolumab    -   ANA (if result is positive, check ESR and CRP to confirm)    -   Serum cytokine multiplex    -   Selected serum markers    -   Frozen PBMC analysis for characterization of T cells, monocytes        and myeloid-derived suppressor cells by flow cytometry    -   Tumor biopsy samples    -   IHC analysis of selected biomarkers    -   Gene expression analysis    -   T-cell receptor clonality    -   Neo-antigen analysis

Table of Sequences

Table 10 provides certain sequences discussed herein. All polypeptideand antibody sequences are shown without leader sequences, unlessotherwise indicated.

TABLE 10 Sequences and Descriptions SEQ ID NO Description Sequence 1hCSF1R IPVIEPSVPE LVVKPGATVT LRCVGNGSVE WDGPPSPHWT LYSDGSSSIL(full-length, STNNATFQNT GTYRCTEPGD PLGGSAAIHL YVKDPARPWN VLAQEVVVFEno leader DQDALLPCLL TDPVLEAGVS LVRVRGRPLM RHTNYSFSPW HGFTIHRAKFsequence) IQSQDYQCSA LMGGRKVMSI SIRLKVQKVI PGPPALTLVP AELVRIRGEAAQIVCSASSV DVNFDVFLQH NNTKLAIPQQ SDFHNNRYQK VLTLNLDQVDFQHAGNYSCV ASNVQGKHST SMFFRVVESA YLNLSSEQNL IQEVTVGEGLNLKVMVEAYP GLQGFNWTYL GPFSDHQPEP KLANATTKDT YRHTFTLSLPRLKPSEAGRY SFLARNPGGW RALTFELTLR YPPEVSVIWT FINGSGTLLCAASGYPQPNV TWLQCSGHTD RCDEAQVLQV WDDPYPEVLS QEPFHKVTVQSLLTVETLEH NQTYECRAHN SVGSGSWAFI PISAGAHTHP PDEFLFTPVVVACMSIMALL LLLLLLLLYK YKQKPKYQVR WKIIESYEGN SYTFIDPTQLPYNEKWEFPR NNLQFGKTLG AGAFGKVVEA TAFGLGKEDA VLKVAVKMLKSTAHADEKEA LMSELKIMSH LGQHENIVNL LGACTHGGPV LVITEYCCYGDLLNFLRRKA EAMLGPSLSP GQDPEGGVDY KNIHLEKKYV RRDSGFSSQGVDTYVEMRPV STSSNDSFSE QDLDKEDGRP LELRDLLHFS SQVAQGMAFLASKNCIHRDV AARNVLLTNG HVAKIGDFGL ARDIMNDSNY IVKGNARLPVKWMAPESIFD CVYTVQSDVW SYGILLWEIF SLGLNPYPGI LVNSKFYKLVKDGYQMAQPA FAPKNIYSIM QACWALEPTH RPTFQQICSF LQEQAQEDRRERDYTNLPSS SRSGGSGSSS SELEEESSSE HLTCCEQGDI AQPLLQPNNY QFC 2 hCSF1RMGPGVLLLLL VATAWHGQGI PVIEPSVPEL VVKPGATVTL RCVGNGSVEW (full-length, +DGPPSPHWTL YSDGSSSILS TNNATFQNTG TYRCTEPGDP LGGSAAIHLY leaderVKDPARPWNV LAQEVVVFED QDALLPCLLT DPVLEAGVSL VRVRGRPLMR sequence)HTNYSFSPWH GFTIHRAKFI QSQDYQCSAL MGGRKVMSIS IRLKVQKVIPGPPALTLVPA ELVRIRGEAA QIVCSASSVD VNFDVFLQHN NTKLAIPQQSDFHNNRYQKV LTLNLDQVDF QHAGNYSCVA SNVQGKHSTS MFFRVVESAYLNLSSEQNLI QEVTVGEGLN LKVMVEAYPG LQGFNWTYLG PFSDHQPEPKLANATTKDTY RHTFTLSLPR LKPSEAGRYS FLARNPGGWR ALTFELTLRYPPEVSVIWTF INGSGTLLCA ASGYPQPNVT WLQCSGHTDR CDEAQVLQVWDDPYPEVLSQ EPFHKVTVQS LLTVETLEHN QTYECRAHNS VGSGSWAFIPISAGAHTHPP DEFLFTPVVV ACMSIMALLL LLLLLLLYKY KQKPKYQVRWKIIESYEGNS YTFIDPTQLP YNEKWEFPRN NLQFGKTLGA GAFGKVVEATAFGLGKEDAV LKVAVKMLKS TAHADEKEAL MSELKIMSHL GQHENIVNLLGACTHGGPVL VITEYCCYGD LLNFLRRKAE AMLGPSLSPG QDPEGGVDYKNIHLEKKYVR RDSGFSSQGV DTYVEMRPVS TSSNDSFSEQ DLDKEDGRPLELRDLLHFSS QVAQGMAFLA SKNCIHRDVA ARNVLLTNGH VAKIGDFGLARDIMNDSNYI VKGNARLPVK WMAPESIFDC VYTVQSDVWS YGILLWEIFSLGLNPYPGIL VNSKFYKLVK DGYQMAQPAF APKNIYSIMQ ACWALEPTHRPTFQQICSFL QEQAQEDRRE RDYTNLPSSS RSGGSGSSSS ELEEESSSEHLTCCEQGDIA QPLLQPNNYQ FC 5 hCSF1RIPVIEPSVPE LVVKPGATVT LRCVGNGSVE WDGPPSPHWT LYSDGSSSIL ECD.506STNNATFQNT GTYRCTEPGD PLGGSAAIHL YVKDPARPWN VLAQEVVVFEDQDALLPCLL TDPVLEAGVS LVRVRGRPLM RHTNYSFSPW HGFTIHRAKFIQSQDYQCSA LMGGRKVMSI SIRLKVQKVI PGPPALTLVP AELVRIRGEAAQIVCSASSV DVNFDVFLQH NNTKLAIPQQ SDFHNNRYQK VLTLNLDQVDFQHAGNYSCV ASNVQGKHST SMFFRVVESA YLNLSSEQNL IQEVTVGEGLNLKVMVEAYP GLQGFNWTYL GPFSDHQPEP KLANATTKDT YRHTFTLSLPRLKPSEAGRY SFLARNPGGW RALTFELTLR YPPEVSVIWT FINGSGTLLCAASGYPQPNV TWLQCSGHTD RCDEAQVLQV WDDPYPEVLS QEPFHKVTVQSLLTVETLEH NQTYECRAHN SVGSGSWAFI PISAGAH 6 hCSF1RIPVIEPSVPE LVVKPGATVT LRCVGNGSVE WDGPPSPHWT LYSDGSSSIL ECD.506-FcSTNNATFQNT GTYRCTEPGD PLGGSAAIHL YVKDPARPWN VLAQEVVVFEDQDALLPCLL TDPVLEAGVS LVRVRGRPLM RHTNYSFSPW HGFTIHRAKFIQSQDYQCSA LMGGRKVMSI SIRLKVQKVI PGPPALTLVP AELVRIRGEAAQIVCSASSV DVNFDVFLQH NNTKLAIPQQ SDFHNNRYQK VLTLNLDQVDFQHAGNYSCV ASNVQGKHST SMFFRVVESA YLNLSSEQNL IQEVTVGEGLNLKVMVEAYP GLQGFNWTYL GPFSDHQPEP KLANATTKDT YRHTFTLSLPRLKPSEAGRY SFLARNPGGW RALTFELTLR YPPEVSVIWT FINGSGTLLCAASGYPQPNV TWLQCSGHTD RCDEAQVLQV WDDPYPEVLS QEPFHKVTVQSLLTVETLEH NQTYECRAHN SVGSGSWAFI PISAGAHEPK SSDKTHTCPPCPAPELLGGP SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVKFNWYVDGVEVHNAK TKPREEQYNS TYRVVSVLTV LHQDWLNGKE YKCKVSNKALPAPIEKTISK AKGQPREPQV YTLPPSRDEL TKNQVSLTCL VKGFYPSDIAVEWESNGQPE NNYKTTPPVL DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVMHEALHNHYTQ KSLSLSPGK 7 cynoCSF1RMGPGVLLLLL VVTAWHGQGI PVIEPSGPEL VVKPGETVTL RCVGNGSVEW ECD (withDGPISPHWTL YSDGPSSVLT TTNATFQNTR TYRCTEPGDP LGGSAAIHLY leaderVKDPARPWNV LAKEVVVFED QDALLPCLLT DPVLEAGVSL VRLRGRPLLR sequence)HTNYSFSPWH GFTIHRAKFI QGQDYQCSAL MGSRKVMSIS IRLKVQKVIPGPPALTLVPA ELVRIRGEAA QIVCSASNID VDFDVFLQHN TTKLAIPQRSDFHDNRYQKV LTLSLGQVDF QHAGNYSCVA SNVQGKHSTS MFFRVVESAYLDLSSEQNLI QEVTVGEGLN LKVMVEAYPG LQGFNWTYLG PFSDHQPEPKLANATTKDTY RHTFTLSLPR LKPSEAGRYS FLARNPGGWR ALTFELTLRYPPEVSVIWTS INGSGTLLCA ASGYPQPNVT WLQCAGHTDR CDEAQVLQVWVDPHPEVLSQ EPFQKVTVQS LLTAETLEHN QTYECRAHNS VGSGSWAFIP ISAGAR 8cynoCSF1R MGPGVLLLLL VVTAWHGQGI PVIEPSGPEL VVKPGETVTL RCVGNGSVEW ECD-FcDGPISPHWTL YSDGPSSVLT TTNATFQNTR TYRCTEPGDP LGGSAAIHLY (with leaderVKDPARPWNV LAKEVVVFED QDALLPCLLT DPVLEAGVSL VRLRGRPLLR sequence)HTNYSFSPWH GFTIHRAKFI QGQDYQCSAL MGSRKVMSIS IRLKVQKVIPGPPALTLVPA ELVRIRGEAA QIVCSASNID VDFDVFLQHN TTKLAIPQRSDFHDNRYQKV LTLSLGQVDF QHAGNYSCVA SNVQGKHSTS MFFRVVESAYLDLSSEQNLI QEVTVGEGLN LKVMVEAYPG LQGFNWTYLG PFSDHQPEPKLANATTKDTY RHTFTLSLPR LKPSEAGRYS FLARNPGGWR ALTFELTLRYPPEVSVIWTS INGSGTLLCA ASGYPQPNVT WLQCAGHTDR CDEAQVLQVWVDPHPEVLSQ EPFQKVTVQS LLTAETLEHN QTYECRAHNS VGSGSWAFIPISAGARGSEP KSSDKTHTCP PCPAPELLGG PSVFLFPPKP KDTLMISRTPEVTCVVVDVS HEDPEVKFNW YVDGVEVHNA KTKPREEQYN STYRVVSVLTVLHQDWLNGK EYKCKVSNKA LPAPIEKTIS KAKGQPREPQ VYTLPPSRDELTKNQVSLTC LVKGFYPSDI AVEWESNGQP ENNYKTTPPV LDSDGSFFLYSKLTVDKSRW QQGNVFSCSV MHEALHNHYT QKSLSLSPGK 3 Light chainMETDTLLLWV LLLWVPGSTG leader sequence 4 Heavy chain MAVLGLLLCL VTFPSCVLSleader sequence 9 Fab 0301EVQLQQSGPE LVRPGASVKM SCKASGYTFT DNYMIWVKQS HGKSLEWIGD heavy chainINPYNGGTTF NQKFKGKATL TVEKSSSTAY MQLNSLTSED SAVYYCARES variablePYFSNLYVMD YWGQGTSVTV SS region 10 Fab 0301NIVLTQSPAS LAVSLGQRAT ISCKASQSVD YDGDNYMNWY QQKPGQPPKL light chainLIYAASNLES GIPARFSGSG SGTDFTLNIH PVEEEDAATY YCHLSNEDLS variableTFGGGTKLEI K region 11 Fab 0302EIQLQQSGPE LVKPGASVKM SCKASGYTFS DFNIHWVKQK PGQGLEWIGY heavy chainINPYTDVTVY NEKFKGKATL TSDRSSSTAY MDLSSLTSED SAVYYCASYF variableDGTFDYALDY WGQGTSITVS S region 12 Fab 0302DVVVTQTPAS LAVSLGQRAT ISCRASESVD NYGLSFMNWF QQKPGQPPKL light chainLIYTASNLES GIPARFSGGG SRTDFTLTID PVEADDAATY FCQQSKELPW variableTFGGGTRLEI K region 13 Fab 0311EIQLQQSGPD LMKPGASVKM SCKASGYIFT DYNMHWVKQN QGKSLEWMGE heavy chainINPNNGVVVY NQKFKGTTTL TVDKSSSTAY MDLHSLTSED SAVYYCTRAL variableYHSNFGWYFD SWGKGTTLTV SS region 14 Fab 0311DIVLTQSPAS LAVSLGQRAT ISCKASQSVD YDGDSHMNWY QQKPGQPPKL light chainLIYTASNLES GIPARFSGSG SGADFTLTIH PVEEEDAATY YCQQGNEDPW variableTFGGGTRLEI K region 15 0301 heavy GYTFTDNYMI chain CDR1 16 0301 heavyDINPYNGGTT FNQKFKG chain CDR2 17 0301 heavy ESPYFSNLYV MDY chain CDR3 180301 light KASQSVDYDG DNYMN chain CDR1 19 0301 light AASNLES chain CDR220 0301 light HLSNEDLST chain CDR3 21 0302 heavy GYTFSDFNIH chain CDR122 0302 heavy YINPYTDVTV YNEKFKG chain CDR2 23 0302 heavy YFDGTFDYAL DYchain CDR3 24 0302 light RASESVDNYG LSFMN chain CDR1 25 0302 lightTASNLES chain CDR2 26 0302 light QQSKELPWT chain CDR3 27 0311 heavyGYIFTDYNMH chain CDR1 28 0311 heavy EINPNNGVVV YNQKFKG chain CDR2 290311 heavy ALYHSNFGWY FDS chain CDR3 30 0311 light KASQSVDYDG DSHMNchain CDR1 31 0311 light TASNLES chain CDR2 32 0311 light QQGNEDPWTchain CDR3 33 cAb 0301EVQLQQSGPE LVRPGASVKM SCKASGYTFT DNYMIWVKQS HGKSLEWIGD heavy chainINPYNGGTTF NQKFKGKATL TVEKSSSTAY MQLNSLTSED SAVYYCARESPYFSNLYVMD YWGQGTSVTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 34 cAb 0301NIVLTQSPAS LAVSLGQRAT ISCKASQSVD YDGDNYMNWY QQKPGQPPKL light chainLIYAASNLES GIPARFSGSG SGTDFTLNIH PVEEEDAATY YCHLSNEDLSTFGGGTKLEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 35 cAb 0302EIQLQQSGPE LVKPGASVKM SCKASGYTFS DFNIHWVKQK PGQGLEWIGY heavy chainINPYTDVTVY NEKFKGKATL TSDRSSSTAY MDLSSLTSED SAVYYCASYFDGTFDYALDY WGQGTSITVS SASTKGPSVF PLAPCSRSTS ESTAALGCLVKDYFPEPVTV SWNSGALTSG VHTFPAVLQS SGLYSLSSVV TVPSSSLGTKTYTCNVDHKP SNTKVDKRVE SKYGPPCPPC PAPEFLGGPS VFLFPPKPKDTLMISRTPEV TCVVVDVSQE DPEVQFNWYV DGVEVHNAKT KPREEQFNSTYRVVSVLTVL HQDWLNGKEY KCKVSNKGLP SSIEKTISKA KGQPREPQVYTLPPSQEEMT KNQVSLTCLV KGFYPSDIAV EWESNGQPEN NYKTTPPVLDSDGSFFLYSR LTVDKSRWQE GNVFSCSVMH KALHNHYTQK SLSLSLGK 36 cAb 0302DVVVTQTPAS LAVSLGQRAT ISCRASESVD NYGLSFMNWF QQKPGQPPKL light chainLIYTASNLES GIPARFSGGG SRTDFTLTID PVEADDAATY FCQQSKELPWTFGGGTRLEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 37 cAb 0311EIQLQQSGPD LMKPGASVKM SCKASGYIFT DYNMHWVKQN QGKSLEWMGE heavy chainINPNNGVVVY NQKFKGTTTL TVDKSSSTAY MDLHSLTSED SAVYYCTRALYHSNFGWYFD SWGKGTTLTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 38 cAb 0311DIVLTQSPAS LAVSLGQRAT ISCKASQSVD YDGDSHMNWY QQKPGQPPKL light chainLIYTASNLES GIPARFSGSG SGADFTLTIH PVEEEDAATY YCQQGNEDPWTFGGGTRLEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 39 h0301-H0QVQLVQSGAE VKKPGSSVKV SCKASGYTFT DNYMIWVRQA PGQGLEWMGD heavy chainINPYNGGTTF NQKFKGRVTI TADKSTSTAY MELSSLRSED TAVYYCARES variablePYFSNLYVMD YWGQGTLVTV SS region 40 h0301-H1QVQLVQSGAE VKKPGSSVKV SCKASGYTFT DNYMIWVRQA PGQGLEWMGD heavy chainINPYNGGTTF NQKFKGRVTI TVDKSTSTAY MELSSLRSED TAVYYCARES variablePYFSNLYVMD YWGQGTLVTV SS region 41 h0301-H2QVQLVQSGAE VKKPGSSVKV SCKASGYTFT DNYMIWVRQA PGQGLEWIGD heavy chainINPYNGGTTF NQKFKGRATL TVDKSTSTAY MELSSLRSED TAVYYCARES variablePYFSNLYVMD YWGQGTLVTV SS region 42 H0302-H1QVQLVQSGAE VKKPGSSVKV SCKASGYTFS DFNIHWVRQA PGQGLEWMGY heavy chainINPYTDVTVY NEKFKGRVTI TSDKSTSTAY MELSSLRSED TAVYYCASYF variableDGTFDYALDY WGQGTLVTVS S region 43 H0302-H2QVQLVQSGAE VKKPGSSVKV SCKASGYTFS DFNIHWVRQA PGQGLEWIGY heavy chainINPYTDVTVY NEKFKGRATL TSDKSTSTAY MELSSLRSED TAVYYCASYF variableDGTFDYALDY WGQGTLVTVS S region 44 H0311-H1QVQLVQSGAE VKKPGSSVKV SCKASGYIFT DYNMHWVRQA PGQGLEWMGE heavy chainINPNNGVVVY NQKFKGRVTI TVDKSTSTAY MELSSLRSED TAVYYCTRAL variableYHSNFGWYFD SWGQGTLVTV SS region 45 H0311-H2QVQLVQSGAE VKKPGSSVKV SCKASGYIFT DYNMHWVRQA PGQGLEWMGE heavy chainINPNNGVVVY NQKFKGTTTL TVDKSTSTAY MELSSLRSED TAVYYCTRAL variableYHSNFGWYFD SWGQGTLVTV SS region 46 H0301-L0EIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDNYMNWY QQKPGQAPRL light chainLIYAASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCHLSNEDLS variableTFGGGTKVEI K region 47 H0301-L1NIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDNYMNWY QQKPGQAPRL light chainLIYAASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCHLSNEDLS variableTFGGGTKVEI K region 48 H0302-L0EIVLTQSPAT LSLSPGERAT LSCRASESVD NYGLSFMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCQQSKELPW variableTFGQGTKVEI K region 49 H0302-L1EIVLTQSPAT LSLSPGERAT LSCRASESVD NYGLSFMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SRTDFTLTIS SLEPEDFAVY YCQQSKELPW variableTFGQGTKVEI K region 50 H0302-L2EIVVTQSPAT LSLSPGERAT LSCRASESVD NYGLSFMNWF QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SRTDFTLTIS SLEPEDFAVY YCQQSKELPW variableTFGQGTKVEI K region 51 H0311-L0EIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDSHMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCQQGNEDPW variableTFGQGTKVEI K region 52 H0311-L1DIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDSHMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SGADFTLTIS SLEPEDFAVY YCQQGNEDPW variableTFGQGTKVEI K region 53 h0301-H0QVQLVQSGAE VKKPGSSVKV SCKASGYTFT DNYMIWVRQA PGQGLEWMGD heavy chainINPYNGGTTF NQKFKGRVTI TADKSTSTAY MELSSLRSED TAVYYCARESPYFSNLYVMD YWGQGTLVTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 54 h0301-H1QVQLVQSGAE VKKPGSSVKV SCKASGYTFT DNYMIWVRQA PGQGLEWMGD heavy chainINPYNGGTTF NQKFKGRVTI TVDKSTSTAY MELSSLRSED TAVYYCARESPYFSNLYVMD YWGQGTLVTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 55 h0301-H2QVQLVQSGAE VKKPGSSVKV SCKASGYTFT DNYMIWVRQA PGQGLEWIGD heavy chainINPYNGGTTF NQKFKGRATL TVDKSTSTAY MELSSLRSED TAVYYCARESPYFSNLYVMD YWGQGTLVTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 56 H0302-H1QVQLVQSGAE VKKPGSSVKV SCKASGYTFS DFNIHWVRQA PGQGLEWMGY heavy chainINPYTDVTVY NEKFKGRVTI TSDKSTSTAY MELSSLRSED TAVYYCASYFDGTFDYALDY WGQGTLVTVS SASTKGPSVF PLAPCSRSTS ESTAALGCLVKDYFPEPVTV SWNSGALTSG VHTFPAVLQS SGLYSLSSVV TVPSSSLGTKTYTCNVDHKP SNTKVDKRVE SKYGPPCPPC PAPEFLGGPS VFLFPPKPKDTLMISRTPEV TCVVVDVSQE DPEVQFNWYV DGVEVHNAKT KPREEQFNSTYRVVSVLTVL HQDWLNGKEY KCKVSNKGLP SSIEKTISKA KGQPREPQVYTLPPSQEEMT KNQVSLTCLV KGFYPSDIAV EWESNGQPEN NYKTTPPVLDSDGSFFLYSR LTVDKSRWQE GNVFSCSVMH EALHNHYTQK SLSLSLGK 57 H0302-H2QVQLVQSGAE VKKPGSSVKV SCKASGYTFS DFNIHWVRQA PGQGLEWIGY heavy chainINPYTDVTVY NEKFKGRATL TSDKSTSTAY MELSSLRSED TAVYYCASYFDGTFDYALDY WGQGTLVTVS SASTKGPSVF PLAPCSRSTS ESTAALGCLVKDYFPEPVTV SWNSGALTSG VHTFPAVLQS SGLYSLSSVV TVPSSSLGTKTYTCNVDHKP SNTKVDKRVE SKYGPPCPPC PAPEFLGGPS VFLFPPKPKDTLMISRTPEV TCVVVDVSQE DPEVQFNWYV DGVEVHNAKT KPREEQFNSTYRVVSVLTVL HQDWLNGKEY KCKVSNKGLP SSIEKTISKA KGQPREPQVYTLPPSQEEMT KNQVSLTCLV KGFYPSDIAV EWESNGQPEN NYKTTPPVLDSDGSFFLYSR LTVDKSRWQE GNVFSCSVMH EALHNHYTQK SLSLSLGK 58 H0311-H1QVQLVQSGAE VKKPGSSVKV SCKASGYIFT DYNMHWVRQA PGQGLEWMGE heavy chainINPNNGVVVY NQKFKGRVTI TVDKSTSTAY MELSSLRSED TAVYYCTRALYHSNFGWYFD SWGQGTLVTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 59 H0311-H2QVQLVQSGAE VKKPGSSVKV SCKASGYIFT DYNMHWVRQA PGQGLEWMGE heavy chainINPNNGVVVY NQKFKGTTTL TVDKSTSTAY MELSSLRSED TAVYYCTRALYHSNFGWYFD SWGQGTLVTV SSASTKGPSV FPLAPCSRST SESTAALGCLVKDYFPEPVT VSWNSGALTS GVHTFPAVLQ SSGLYSLSSV VTVPSSSLGTKTYTCNVDHK PSNTKVDKRV ESKYGPPCPP CPAPEFLGGP SVFLFPPKPKDTLMISRTPE VTCVVVDVSQ EDPEVQFNWY VDGVEVHNAK TKPREEQFNSTYRVVSVLTV LHQDWLNGKE YKCKVSNKGL PSSIEKTISK AKGQPREPQVYTLPPSQEEM TKNQVSLTCL VKGFYPSDIA VEWESNGQPE NNYKTTPPVLDSDGSFFLYS RLTVDKSRWQ EGNVFSCSVM HEALHNHYTQ KSLSLSLGK 60 h0301-L0EIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDNYMNWY QQKPGQAPRL light chainLIYAASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCHLSNEDLSTFGGGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 61 h0301-L1NIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDNYMNWY QQKPGQAPRL light chainLIYAASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCHLSNEDLSTFGGGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 62 H0302-L0EIVLTQSPAT LSLSPGERAT LSCRASESVD NYGLSFMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCQQSKELPWTFGQGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 63 H0302-L1EIVLTQSPAT LSLSPGERAT LSCRASESVD NYGLSFMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SRTDFTLTIS SLEPEDFAVY YCQQSKELPWTFGQGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 64 H0302-L2EIVVTQSPAT LSLSPGERAT LSCRASESVD NYGLSFMNWF QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SRTDFTLTIS SLEPEDFAVY YCQQSKELPWTFGQGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 65 H0311-L0EIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDSHMNWY QQKPGQAPRL light chainLIYTASNLES GIPARFSGSG SGTDFTLTIS SLEPEDFAVY YCQQGNEDPWTFGQGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 66 H0311-L1DIVLTQSPAT LSLSPGERAT LSCKASQSVD YDGDSHMNWY QQKPGQAPRL hght chainLIYTASNLES GIPARFSGSG SGADFTLTIS SLEPEDFAVY YCQQGNEDPWTFGQGTKVEI KRTVAAPSVF IFPPSDEQLK SGTASVVCLL NNFYPREAKVQWKVDNALQS GNSQESVTEQ DSKDSTYSLS STLTLSKADY EKHKVYACEVTHQGLSSPVT KSFNRGEC 67 HumanEEVSEYCSHM IGSGHLQSLQ RLIDSQMETS CQITFEFVDQ EQLKDPVCYL CSF1KKAFLLVQDI MEDTMRFRDN TPNAIAIVQL QELSLRLKSC FTKDYEEHDKACVRTFYETP LQLLEKVKNV FNETKNLLDK DWNIFSKNCN NSFAECSSQG HERQSEGS 68 HumanNEPLEMWPLT QNEECTVTGF LRDKLQYRSR LQYMKHYFPI NYKISVPYEG IL-34VFRIANVTRL QRAQVSEREL RYLWVLVSLSATESVQDVLL EGHPSWKYLQEVQTLLLNVQ QGLTDVEVSP KVESVLSLLN APGPNLKLVR PKALLDNCFRVMELLYCSCC KQSSVLNWQD CEVPSPQSCS PEPSLQYAAT QLYPPPPWSPSSPPHSTGSV RPVRAQGEGL LP 69 Human QVQLVQSGAE VKKPGSSVKV SCKAS acceptor AFR1 70 Human WVRQAPGQGL EWMG acceptor A FR2 71 HumanRVTITADKST STAYMELSSL RSEDTAVYYC AR acceptor A FR3 72 Human WGQGTLVTVS Sacceptor A FR4 73 Human QVQLVQSGAE VKKPGSSVKV SCKAS acceptor B FR1 74Human WVRQAPGQGL EWMG acceptor B FR2 75 HumanRVTITADKST STAYMELSSL RSEDTAVYYC AR acceptor B FR3 76 Human WGQGTLVTVSSacceptor B FR4 77 Human QVQLVQSGAE VKKPGSSVKV SCKAS acceptor C FR1 78Human WVRQAPGQGL EWMG acceptor C FR2 79 HumanRVTITADKST STAYMELSSL RSEDTAVYYC AR acceptor C FR3 80 Human WGQGTLVTVS Sacceptor C FR4 81 Human EIVLTQSPAT LSLSPGERAT LSC acceptor D FR1 82Human WYQQKPGQAP RLLIY acceptor D FR2 83 HumanGIPARFSGSG SGTDFTLTIS SLEPEDFAVY YC acceptor D FR3 84 Human FGGGTKVEIKacceptor D FR4 85 Human EIVLTQSPAT LSLSPGERAT LSC acceptor E FR1 86Human WYQQKPGQAP RLLIY acceptor E FR2 87 HumanGIPARFSGSG SGTDFTLTIS SLEPEDFAVY YC acceptor E FR3 88 Human FGQGTKVEIKacceptor E FR4 89 Human EIVLTQSPAT LSLSPGERAT LSC acceptor F FR1 90Human WYQQKPGQAP RLLIY acceptor F FR2 91 HumanGIPARFSGSG SGTDFTLTIS SLEPEDFAVY YC acceptor F FR3 92 Human FGQGTKVEIKacceptor F FR4 93 mCSF1RAPVIEPSGPE LVVEPGETVT LRCVSNGSVE WDGPISPYWT LDPESPGSTL ECD-FcTTRNATFKNT GTYRCTELED PMAGSTTIHL YVKDPAHSWN LLAQEVTVVEGQEAVLPCLI TDPALKDSVS LMREGGRQVL RKTVYFFSPW RGFIIRKAKVLDSNTYVCKT MVNGRESTST GIWLKVNRVH PEPPQIKLEP SKLVRIRGEAAQIVCSATNA EVGFNVILKR GDTKLEIPLN SDFQDNYYKK VRALSLNAVDFQDAGIYSCV ASNDVGTRTA TMNFQVVESA YLNLTSEQSL LQEVSVGDSLILTVHADAYP SIQHYNWTYL GPFFEDQRKL EFITQRAIYR YTFKLFLNRVKASEAGQYFL MAQNKAGWNN LTFELTLRYP PEVSVTWMPV NGSDVLFCDVSGYPQPSVTW MECRGHTDRC DEAQALQVWN DTHPEVLSQK PFDKVIIQSQLPIGTLKHNM TYFCKTHNSV GNSSQYFRAV SLGQSKQEPK SSDKTHTCPPCPAPELLGGP SVFLFPPKPK DTLMISRTPE VTCVVVDVSH EDPEVKFNWYVDGVEVHNAK TKPREEQYNS TYRVVSVLTV LHQDWLNGKE YKCKVSNKALPAPIEKTISK AKGQPREPQV YTLPPSRDEL TKNQVSLTCL VKGFYPSDIAVEWESNGQPE NNYKTTPPVL DSDGSFFLYS KLTVDKSRWQ QGNVFSCSVMHEALHNHYTQ KSLSLSPGK 94 HumanASTKGPSVFP LAPCSRSTSE STAALGCLVK DYFPEPVTVS WNSGALTSGV IgG4 S241PHTFPAVLQSS GLYSLSSVVT VPSSSLGTKT YTCNVDHKPS NTKVDKRVESKYGPPCPPCP APEFLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSQEDPEVQFNWYVD GVEVHNAKTK PREEQFNSTY RVVSVLTVLH QDWLNGKEYKCKVSNKGLPS SIEKTISKAK GQPREPQVYT LPPSQEEMTK NQVSLTCLVKGFYPSDIAVE WESNGQPENN YKTTPPVLDS DGSFFLYSRL TVDKSRWQEGNVFSCSVMHE ALHNHYTQKS LSLSLGK 95 Human IgκRTVAAPSVFI FPPSDEQLKS GTASVVCLLN NFYPREAKVQ WKVDNALQSGNSQESVTEQD SKDSTYSLSS TLTLSKADYE KHKVYACEVT HQGLSSPVTK SFNRGEC 96human PD-1 MQIPQAPWPV VWAVLQLGWR PGWFLDSPDR PWNPPTFSPA LLVVTEGDNAprecursor TFTCSFSNTS ESFVLNWYRM SPSNQTDKLA AFPEDRSQPG QDCRFRVTQL(with signal PNGRDFHMSV VRARRNDSGT YLCGAISLAP KAQIKESLRA ELRVTERRAEsequence) VPTAHPSPSP RPAGQFQTLV VGVVGGLLGS LVLLVWVLAV ICSRAARGTIUniProtKB/ GARRTGQPLK EDPSAVPVFS VDYGELDFQW REKTPEPPVP CVPEQTEYATSwiss-Prot: IVFPSGMGTS SPARRGSADG PRSAQPLRPE DGHCSWPL Q15116.3,01-OCT-2014 97 human PD-1PGWFLDSPDR PWNPPTFSPA LLVVTEGDNA TFTCSFSNTS ESFVLNWYRM (mature,SPSNQTDKLA AFPEDRSQPG QDCRFRVTQL PNGRDFHMSV VRARRNDSGT withoutYLCGAISLAP KAQIKESLRA ELRVTERRAE VPTAHPSPSP RPAGQFQTLV signalVGVVGGLLGS LVLLVWVLAV ICSRAARGTI GARRTGQPLK EDPSAVPVFS sequence)VDYGELDFQW REKTPEPPVP CVPEQTEYAT IVFPSGMGTS SPARRGSADGPRSAQPLRPE DGHCSWPL 98 human PD-MRIFAVFIFM TYWHLLNAFT VTVPKDLYVV EYGSNMTIEC KFPVEKQLDL L1 precursorAALIVYWEME DKNIIQFVHG EEDLKVQHSS YRQRARLLKD QLSLGNAALQ (with signalITDVKLQDAG VYRCMISYGG ADYKRITVKV NAPYNKINQR ILVVDPVTSE sequence)HELTCQAEGY PKAEVIWTSS DHQVLSGKTT TTNSKREEKL FNVTSTLRIN UniProtKB/TTTNEIFYCT FRRLDPEENH TAELVIPELP LAHPPNERTH LVILGAILLC Swiss-Prot:LGVALTFIFR LRKGRMMDVK KCGIQDTNSK KQSDTHLEET Q9NZQ7.1, 01-OCT-2014 99human PD- FT VTVPKDLYVV EYGSNMTIEC KFPVEKQLDL AALIVYWEME L1 (mature,DKNIIQFVHG EEDLKVQHSS YRQRARLLKD QLSLGNAALQ ITDVKLQDAG withoutVYRCMISYGG ADYKRITVKV NAPYNKINQR ILVVDPVTSE HELTCQAEGY signalPKAEVIWTSS DHQVLSGKTT TTNSKREEKL FNVTSTLRIN TTTNEIFYCT sequence)FRRLDPEENH TAELVIPELP LAHPPNERTH LVILGAILLC LGVALTFIFRLRKGRMMDVK KCGIQDTNSK KQSDTHLEET 100 NivolumabQVQLVESGGGVVQPGRSLRLDCKASGITFSNSGMHWVRQAPGKGLEWVAVIWYD heavy chainGSKRYYADSVKGRFTISRDNSKNTLFLQMNSLRAEDTAVYYCATNDDYWGQGTL variable VTVSSregion 101 NivolumabASTKGPSVFPLAPCSRSTSESTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFP heavy chainAVLQSSGLYSLSSVVTVPSSSLGTKTYTCNVDHKPSNTKVDKRVESKYGPPCPP constantCPAPEFLGGPSVFLFPPKPKDTLMISRTPEVTCVVVDVSQEDPEVQFNWYVDGV regionEVHNAKTKPREEQFNSTYRVVSVLTVLHQDWLNGKEYKCKVSNKGLPSSIEKTISKAKGQPREPQVYTLPPSQEEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFFLYSRLTVDKSRWQEGNVFSCSVMHEALHNHYTQKSLSLS LGK 102 NivolumabEIVLTQSPATLSLSPGERATLSCRASQSVSSYLAWYQQKPGQAPRLLIYDASNR light chainATGIPARFSGSGSGTDFTLTISSLEPEDFAVYYCQQSSNWPRTFGQGTKVEIK variable region103 Nivolumab RTVAAPSVFIFPPSDEQLKSGTASVVCLLNNFYPREAKVQWKVDNALQSGNSQElight chain SVTEQDSKDSTYSLSSTLTLSKADYEKHKVYACEVTHQGLSSPVTKSFNRGECconstant region 104 Nivolumab QVQLVESGGGVVQPGRSLRLDCKASGITFS heavy chainvariable region FR1 105 Nivolumab NSGMH heavy chain variable region CDR1106 Nivolumab WVRQAPGKGLEWVA heavy chain variable region FR2 107Nivolumab VIWYDGSKRYYADSVKG heavy chain variable region CDR2 108Nivolumab RFTISRDNSKNTLFLQMNSLRAEDTAVYYCAT heavy chain variableregion FR3 109 Nivolumab NDDY heavy chain variable region CDR3 110Nivolumab WGQGTLVTVSS heavy chain variable region FR4 111 NivolumabEIVLTQSPATLSLSPGERATLSC light chain variable region FR1 112 NivolumabRASQSVSSYLA light chain variable region CDR1 113 NivolumabWYQQKPGQAPRLLIY light chain variable region FR2 114 Nivolumab DASNRATlight chain variable region CDR2 115 NivolumabGIPARFSGSGSGTDFTLTISSLEPEDFAVYYC light chain variable region FR3 116Nivolumab QQSSNWPRT light chain variable region CDR3 117 NivolumabFGQGTKVEIK light chain variable region FR4

1. A method of treating cancer in a subject comprising administering tothe subject a therapeutically effective amount of an anti-CSF1R antibodyand a PD-1/PD-L1 inhibitor, wherein the anti-CSF1R antibody is selectedfrom: a) an antibody comprising a heavy chain comprising the sequence ofeither SEQ ID NO: 42 or 43 and a light chain comprising the sequence ofeither SEQ ID NO: 48, 49, or 50; b) an antibody comprising a heavy chaincomprising a heavy chain (HC) CDR1 having the sequence of SEQ ID NO: 21,an HC CDR2 having the sequence of SEQ ID NO: 22, and an HC CDR3 havingthe sequence of SEQ ID NO: 23, and a light chain comprising a lightchain (LC) CDR1 having the sequence of SEQ ID NO: 24, a LC CDR2 havingthe sequence of SEQ ID NO: 52, and a LC CDR3 having the sequence of SEQID NO: 26; and c) an antibody comprising a heavy chain comprising thesequence of either SEQ ID NO: 56 or 57 and a light chain comprising thesequence of either SEQ ID NO: 62, 63, or 64; and wherein the PD-1/PD-L1inhibitor is an anti-PD-1 antibody selected from: a) an antibodycomprising a heavy chain comprising the sequence of SEQ ID NO: 100 and alight chain comprising the sequence of SEQ ID NO: 102; b) an antibodycomprising a heavy chain comprising a heavy chain (HC) CDR1 having thesequence of SEQ ID NO: 105, an HC CDR2 having the sequence of SEQ ID NO:107, and an HC CDR3 having the sequence of SEQ ID NO: 109, and a lightchain comprising a light chain (LC) CDR1 having the sequence of SEQ IDNO: 112, a LC CDR2 having the sequence of SEQ ID NO: 114, and a LC CDR3having the sequence of SEQ ID NO: 116; c) an antibody comprising a heavychain comprising the sequences of SEQ ID NOs: 100 and 101 and a lightchain comprising the sequences of SEQ ID NOs: 102 and 103; and d)nivolumab. 2.-14. (canceled)
 15. The method of claim 1, wherein theanti-CSF1R antibody and the PD-1/PD-L1 inhibitor are administeredconcurrently or sequentially.
 16. The method of claim 1, wherein theanti-CSF1R antibody and the PD-1/PD-L1 inhibitor are administeredconcurrently.
 17. The method of claim 15, wherein one or more doses ofthe PD-1/PD-L1 inhibitor are administered prior to administering theanti-CSF1R antibody.
 18. The method of claim 17, wherein the subjectreceived a complete course of PD-1/PD-L1 inhibitor therapy prior toadministration of the anti-CSF1R antibody.
 19. The method of claim 18,wherein the anti-CSF1R antibody is administered during a second courseof PD-1/PD-L1 inhibitor therapy.
 20. The method of claim 17, wherein thesubject received at least one, at least two, at least three, or at leastfour doses of the PD-1/PD-L1 inhibitor prior to administration of theanti-CSF1R antibody.
 21. The method of claim 1, wherein at least onedose of the PD-1/PD-L1 inhibitor is administered concurrently with theanti-CSF1R inhibitor.
 22. The method of claim 15, wherein one or moredoses of the anti-CSF1R antibody are administered prior to administeringthe PD-1/PD-L1 inhibitor.
 23. The method of claim 22, wherein thesubject received at least two, at least three, at least three, or atleast four doses of the anti-CSF1R antibody prior to administration ofthe PD-1/PD-L1 inhibitor.
 24. The method of claim 22, wherein at leastone dose of the anti-CSF1R antibody is administered concurrently withthe PD-1/PD-L1 inhibitor.
 25. The method of claim 1, wherein theanti-CSF1R antibody is administered at a dose of about 0.1, about 0.3,about 0.5, about 1, about 2, about 3, about 4, about 5, or about 10mg/kg.
 26. The method of claim 1, wherein the PD-1/PD-L1 inhibitor isadministered at a dose of about 0.5-10 mg/kg, such as at a dose of about0.5, about 1, about 2, about 3, about 4, about 5, or about 10 mg/Kg. 27.The method of claim 1, wherein the anti-CSF1R antibody and thePD-1/PD-L1 inhibitor are administered once per 1, 2, 3, 4, or 5 weeks.28. The method of claim 1, wherein the cancer is selected from non-smallcell lung cancer, melanoma, squamous cell carcinoma of the head andneck, ovarian cancer, pancreatic cancer, renal cell carcinoma,hepatocellular carcinoma, bladder cancer, malignant glioma, colorectalcancer, and endometrial cancer.
 29. The method of claim 28, wherein thecancer is recurrent or progressive after a therapy selected fromsurgery, chemotherapy, radiation therapy, or a combination thereof.30.-35. (canceled)
 36. The method of claim 1, wherein administration ofthe anti-CSF1R antibody and the PD-1/PD-L1 inhibitor results insynergistic inhibition of tumor growth in a mouse model of the cancer.37. The method of claim 36, wherein the cancer is a colon, rectum, orcolorectal cancer and the mouse model comprises colorectal carcinomacells, such as MC38 colorectal carcinoma cells.
 38. The method of claim36, wherein the cancer is a pancreatic cancer and the mouse modelcomprises murine pancreatic ductal adenocarcinoma (PDAC) cells, such asKRas^(G12D)/Ink4a^(−/−) pancreatic ductal adenocarcinoma cells. 39.-64.(canceled)
 65. A method of treating cancer in a subject comprisingadministering to the subject a therapeutically effective amount of ananti-CSF1R antibody and an anti-PD-1 antibody; (a) wherein the cancer isnon-small cell lung cancer (NSCLC), melanoma, squamous cell carcinoma ofthe head and neck (SCCHN), ovarian cancer, renal cell carcinoma, ormalignant glioma; (b) wherein the anti-CSF1R antibody is administered ata dose of about 1, about 2, or about 3 mg/kg every two weeks and theanti-PD-1 antibody is administered at a dose of about 3 mg/kg every twoweeks; (c) wherein the anti-PD-1 antibody is selected from: i) anantibody comprising a heavy chain comprising the sequence of SEQ ID NO:100 and a light chain comprising the sequence of SEQ ID NO: 102; ii) anantibody comprising a heavy chain comprising a heavy chain (HC) CDR1having the sequence of SEQ ID NO: 105, an HC CDR2 having the sequence ofSEQ ID NO: 107, and an HC CDR3 having the sequence of SEQ ID NO: 109,and a light chain comprising a light chain (LC) CDR1 having the sequenceof SEQ ID NO: 112, a LC CDR2 having the sequence of SEQ ID NO: 114, anda LC CDR3 having the sequence of SEQ ID NO: 116; and iii) an antibodycomprising a heavy chain comprising the sequences of SEQ ID NOs: 100 and101 and a light chain comprising the sequences of SEQ ID NOs: 102 and103; and (d) wherein the anti-CSF1R antibody is selected from: i) anantibody comprising a heavy chain comprising the sequence of either SEQID NO: 42 or 43 and a light chain comprising the sequence of either SEQID NO: 48, 49, or 50; ii) an antibody comprising a heavy chaincomprising a heavy chain (HC) CDR1 having the sequence of SEQ ID NO: 21,an HC CDR2 having the sequence of SEQ ID NO: 22, and an HC CDR3 havingthe sequence of SEQ ID NO: 23, and a light chain comprising a lightchain (LC) CDR1 having the sequence of SEQ ID NO: 24, a LC CDR2 havingthe sequence of SEQ ID NO: 25, and a LC CDR3 having the sequence of SEQID NO: 26; and iii) an antibody comprising a heavy chain comprising thesequence of either SEQ ID NO: 56 or 57 and a light chain comprising thesequence of either SEQ ID NO: 62, 63, or
 64. 66. The method of claim 65,wherein the anti-PD-1 antibody comprises a heavy chain comprising thesequences of SEQ ID NOs: 100 and 101 and a light chain comprising thesequences of SEQ ID NOs: 102 and
 103. 67. The method of claim 65,wherein the anti-CSF1R antibody comprises a heavy chain comprising thesequence of either SEQ ID NO: 56 or 57 and a light chain comprising thesequence of either SEQ ID NO: 62, 63, or
 64. 68. A method of treatingcancer in a subject comprising administering to the subject atherapeutically effective amount of an anti-CSF1R antibody andnivolumab; (a) wherein the cancer is non-small cell lung cancer (NSCLC),melanoma, squamous cell carcinoma of the head and neck (SCCHN), ovariancancer, renal cell carcinoma, or malignant glioma; (b) wherein theanti-CSF1R antibody is administered at a dose of about 1, about 2, orabout 3 mg/kg every two weeks and nivolumab is administered at a dose ofabout 3 mg/kg every two weeks; and (d) wherein the anti-CSF1R antibodyis selected from: i) an antibody comprising a heavy chain comprising thesequence of either SEQ ID NO: 42 or 43 and a light chain comprising thesequence of either SEQ ID NO: 48, 49, or 50; ii) an antibody comprisinga heavy chain comprising a heavy chain (HC) CDR1 having the sequence ofSEQ ID NO: 21, an HC CDR2 having the sequence of SEQ ID NO: 22, and anHC CDR3 having the sequence of SEQ ID NO: 23, and a light chaincomprising a light chain (LC) CDR1 having the sequence of SEQ ID NO: 24,a LC CDR2 having the sequence of SEQ ID NO: 25, and a LC CDR3 having thesequence of SEQ ID NO: 26; and iii) an antibody comprising a heavy chaincomprising the sequence of either SEQ ID NO: 56 or 57 and a light chaincomprising the sequence of either SEQ ID NO: 62, 63, or
 64. 69. Themethod of claim 1, wherein the anti-PD-1 antibody is nivolumab.
 70. Themethod of claim 1, wherein the anti-CSF1R antibody comprises a heavychain comprising the sequence of either SEQ ID NO: 56 or 57 and a lightchain comprising the sequence of either SEQ ID NO: 62, 63, or
 64. 71.The method of claim 20, wherein the subject received one dose of thePD-1/PD-L1 inhibitor prior to administration of the anti-CSF1R antibody.72. The method of claim 25, wherein the anti-CSF1R antibody isadministered at a dose of 1, 2, 3, or 4 mg/kg.
 73. The method of claim26, wherein the PD-1/PD-L1 inhibitor is administered at a dose of 3mg/kg.
 74. The method of claim 73, wherein the anti-CSF1R antibody andthe PD-1/PD-L1 inhibitor are administered every two weeks.
 75. Themethod of claim 73, wherein the anti-CSF1R antibody is administered at adose of 1, 2, 3, or 4 mg/kg.
 76. The method of claim 75, wherein theanti-CSF1R antibody and the PD-1/PD-L1 inhibitor are administered everytwo weeks.